Distinctive Writing Styles of ChatGPT and Gemini AI Revealed

It never fails to amuse me just how much we humans love spotting patterns, even when it comes to the quirks of our own language. Take a crowded café or a group chat: it’s clear as daylight that each person types or speaks with their own particular style. But what you might not have realised, at least before reading this, is that artificial intelligences—like ChatGPT and Gemini AI—also possess their very own writing styles. A rather fascinating discovery if you ask me! Drawing on recent linguistic research led by Dr Karolina Rudnicka of the University of Gdańsk, let’s unravel how these digital personalities manifest in the AI realm, why it matters, and what implications this could have across business, marketing, and education.

The Human Touch: Linguistic Roots of Style

What is an Idiolect?

Before jumping head-first into the AI side, I want to touch on the concept of „idiolect.” It’s one of those terms my linguist friends have tossed around with great affection, and it’s surprisingly apt here. An idiolect refers to an individual’s unique way of speaking or writing—a sort of linguistic fingerprint shaped by their first language, age, education, social background, personality, and so much more. Think of it as your signature in words: you may favour certain idioms, sprinkle in Yorkshireisms, or always type with a cheery sign-off.

Now, traditionally, idiolect was considered the domain of humans. Each person, following their own path, weaves their own style. But as it turns out, language models can be caught out the same way—bearing unique, recognisable styles.

The Research Context

In an age where AI-generated content is flying about at record pace, Dr Rudnicka’s work offers the kind of insight that makes you put the kettle on and ponder. By meticulously comparing outputs from ChatGPT and Gemini AI—two of the most popular large language models today—she and her team demonstrated that, much like us, AI systems can develop, or at least exhibit, idiolects. It’s a bit uncanny to admit, but the more I use both, the more I can sense those digital mannerisms too.

Characterising the Personalities of ChatGPT and Gemini AI

The Emergent AI Idiolect

Much as a Scottish Highlander and a Londoner might recount the same story with completely different vibes, language models, too, shape their answers in consistently different ways. These differences aren’t just academic curiosity—they have real, tangible impact on user experience, business communication, and trust.

• Vocabulary & Diction: Some models reach for fancier terminology, while others lean towards everyday speech, peppered with familiar phrases.
• Sentence Structure: You’ll notice some AI platforms develop a knack for tidy, punchy sentences, while others lean into longer, more complex structures. I often find myself recognising the signature “cadence” of each in just a few lines.
• Formality & Tone: One chatbot may maintain a stiff upper lip, never cracking a joke nor straying from polite formality. Another drops a wry quip here and there, sometimes feeling oddly conversational.
• Typical Phrasings: Some models seem to “like” certain stock phrases, almost the way your aunt might always say, “All things considered…”
• Cultural References: While models are both trained on a global flood of data, one may default to American pop culture while another prefers British or more universally recognisable touchstones.

Side-by-Side: ChatGPT vs Gemini AI

After putting both systems through their paces on assorted writing prompts, I couldn’t help noticing a sort of “character” develop. Here’s the gist:

• ChatGPT:
  • Tends to be more narrative, providing detailed background, context, and a “teacher” vibe.
  • Frequent use of transitional phrases like “On the other hand,” or “Let’s take a closer look at…”
  • A fondness for structure—clearly sectioned responses, often garnished with a closing summary.
  • Shows a certain warmth and willingness to embellish, with occasional dabs of informal language.
• Gemini AI:
  • Leans towards succinctness; more clipped, to-the-point sentences.
  • Greater preference for neutrality—less personal, more matter-of-fact.
  • Forms responses with a slightly more technical, analytical tone.
  • Less likely to wander into playful banter, but more likely to clarify, “As an AI model, …”

I found these differences carrying over even (or especially) when generating creative writing or long-form answers. Just as you might spot a friend’s text in a group chat merely by their turn of phrase, after a while, picking out a ChatGPT paragraph from a Gemini-generated one becomes second nature.

Why AI Writing Style Actually Matters

Impacts on Trust and User Experience

In business, marketing, or support roles, what I’ve learned is that consistent style builds trust—regardless of whether it’s coming from a human or a machine. If your brand leans on AI to write blog posts or handle customer enquiries, the underlying „personality” of the bot can (and does) impact how your audience perceives you.

Working with Marketing-Ekspercki, I’ve had plenty of opportunities to test-drive both models for our clients. One thing is crystal clear: people can sniff out inconsistency in tone, especially when it suddenly shifts mid-conversation or across different pages of your site. It’s certainly not a good look if one blog post reads like it was penned by Oscar Wilde and the next by a government job description.

Detecting AI-Generated Content

With public debate swirling around academic honesty, disinformation, and content authenticity, being able to spot an AI’s idiolect is becoming a valued skill. More than once, I’ve found myself looking at an essay and thinking, “Well, that’s a telltale ChatGPT phrase if ever I’ve seen one.”

• For academics and teachers: It’s a new layer of “text forensics,” providing clues about authorship even in a world of faceless writing.
• For businesses: Understanding these digital styles helps ensure AI-generated content aligns with your corporate tone of voice.
• For individuals: It’s simply empowering to read critically, especially as AI content becomes harder to distinguish from human prose.

Practical Implications for Businesses and Marketers

Choosing the Right AI for the Job

As someone responsible for helping businesses select their digital tools, I’m constantly weighing the strengths of different platforms. If a client wants blog posts with a warm, “human” touch, ChatGPT often comes top of my list. For snappy technical copy or FAQ content, Gemini AI may offer more directness.

• Brand Consistency: Matching the right AI to your brand persona ensures readers don’t get whiplash from style shifts.
• Customer Support: Consistent, clear communication—tailored to your target audience—is easier to maintain when you recognise your AI’s output patterns.
• SEO Optimisation: Knowing your AI’s stylistic tendencies helps create content that aligns with both search engine preferences and audience expectations.

Automations and AI Personality

The automations we build for clients at Marketing-Ekspercki, using tools like make.com or n8n, routinely rely on AI-generated copy and responses. The idiolect phenomenon isn’t just academic—understanding your chatbot’s “linguistic quirks” can become a competitive advantage.

Here’s a real-world example from a recent client seeking an automated sales follow-up:

• ChatGPT generated longer, slightly more personal messages, ideal for nurturing warm leads.
• Gemini AI produced concise follow-ups, giving a more professional, „no-nonsense” vibe—perfect for confirming appointments or answering quick queries.

Being tuned in to these nuances meant we could fine-tune the pipeline—something our clients genuinely appreciated.

Raising the Bar: Fine-Tuning Your AI’s Writing Style

Beyond Out-Of-The-Box Outputs

Although AI models arrive with default tendencies, most platforms today offer some degree of control over style through prompt engineering and system messages. I’ve spent more hours than I care to count coaxing models to „speak” with a bit more cheek, or dialling back the formality for younger audiences.

• Prompt Engineering: Small tweaks—asking for simpler language, specifying tone, or even providing writing samples—can nudge an AI closer to your preferred style.
• Post-Editing: Even after generation, a human touch in editing ensures the final product fits snugly with your brand’s established voice.
• System Training: For enterprise-level applications, some opt to train dedicated models or implement „personality layers” for additional customisation.

But here’s the trick—the idiolect doesn’t simply vanish. Just as you might ask a Yorkshireman to fake a London accent (they can try, of course, but certain quirks tend to leak through), the AI’s stylistic traces persist.

The Methods Behind the Research

Quantifying the Uniqueness

Dr Rudnicka’s team approached this subject with painstaking linguistic analysis—measuring not just lexical choices, but sentence patterns and even rhetorical quirks. For the number geeks among us, this involved:

• Stylometric Analysis: Algorithms tally common word and phrase usage, revealing statistically significant patterns unique to a specific AI.
• Comparative Corpora: By cross-referencing output from different AIs and real humans, researchers pinpoint how and where one model diverges from another.
• Blind Testing: Test subjects were asked to identify the „author” (human, ChatGPT, or Gemini) based solely on writing, measuring recognisability rates.

The results? With a little practice, both researchers and lay readers alike can often spot an AI’s Calling Card—its signature style. Even students, with minimal training, managed to distinguish between AI and human authors in controlled tests far more accurately than chance would predict.

Marketing Perspective: Making Style Work for You

Building Brand Identity

In competitive sectors, where content is king, a consistent and appealing tone might just tip the scales. My experience tells me: sticking to an AI model whose writing vibes with your company’s image can be as crucial as choosing your logo or colour palette.

• Brand Guidelines: Spell out acceptable style, humour levels, and cultural references before letting your AI loose on your website.
• Regular Audits: Routinely check for stylistic drift with new updates or model versions; even a slight shift could jar loyal readers.
• Feedback Loops: Use human proofreaders or customer feedback to spot if AI-generated content is veering off-brand.

I recall one e-commerce client whose FAQ page suddenly took on a distinctly more informal, even cheeky tone, after a mid-year update. Only after reviewing our AI pipelines did we realise Gemini had snuck into a previously ChatGPT-only workflow—a quick fix, but a clear lesson!

Maximising Content Impact

When you know your AI, you can tailor content strategies that play to their strengths. ChatGPT excels at engaging stories, explainer blogs, and nurturing emails. Gemini comes into its own for clear-cut product descriptions, analytical summaries, or technical how-tos.

• Long-Form Content: Tap into ChatGPT when you want your brand to sound chatty and approachable.
• Short Social Posts: Gemini’s brevity pays off here—concise, direct, and always on-message.
• Email Marketing: A/B test both, measuring which idiolect resonates better with specific segments.

Educational and Social Implications

Academic Integrity and AI Detection

It’s not just a business concern. Teachers and universities are understandably concerned about AI-generated essays. The ability to spot idiolect markers adds another layer to existing plagiarism checks. In my own workshops, I’ve introduced students to stylometric techniques—many found it surprisingly satisfying to spot the “robotic” quirks of a model’s writing.

• Unexpectedly consistent sentence openings
• Repeated use of format phrases (“Certainly…” “Here’s a summary…”)
• Excessive formality or the odd, slightly stilted turns of phrase

Of course, AIs adapt and improve, but so does human detection skill. I always say: it’s a bit of an arms race, and for now, it favours those who keep their wits sharp.

Cultural Considerations

AI idiolects are shaped by their training data—primarily English-language in both cases, but with subtle tilts towards American or British norms depending on platform and configuration. Sometimes, there’s a heavy American inflection, right down to spelling choices; other times, a European user might notice distinctly British politeness or cultural touchstones.

I find it’s important to watch for accidental cultural mismatches when localising content, especially in markets with strong language preferences. It’s a subtlety, but with real stakes in terms of brand perception and inclusivity.

Where Next? The Future of AI Writing Style

The Arms Race of Authenticity

If there’s one thing I’ve learned about language, it’s this: change is the only constant. As models evolve, their idiolects may become subtler, or even mimic human diversity more convincingly. But they won’t lose their distinctive fingerprints overnight.

• Continued Research: Up-and-coming studies may eventually allow for even more granular identification—spotting not only the presence of AI, but even the specific model and version.
• Customisable Idiolects: Businesses will clamour for bespoke “AI personalities” to reflect their brand—similar to commissioning a custom comic strip style or mascot.
• Greater Transparency: Demands for AI disclosure—“this text was generated by Model X”—will only grow, especially in regulated sectors.

Standing at this fascinating intersection, I’d wager that being “AI-literate”—fluent in the idiolects and style quirks of digital assistants—will quickly join the ranks of essential 21st-century skills. Whether you’re crafting the next marketing campaign or simply reading the morning news, you’ll benefit from understanding the hidden hands shaping the words before you.

One Last Thought

As an English writer, I can say with hand on heart: it’s both exciting and slightly eerie to see computers growing their own literal voices. But as with any language, the more you listen, the more you *hear*. At first, you notice the odd hiccup—maybe an overused phrase, a suspiciously tidy summary—but with time, the personality of each model emerges. And it’s in that familiarity, I dare say, that we not only demystify AI, but put it to better use.

If you’re looking to harness the full spectrum of AI-powered writing for your business, or simply want to keep your eye on the subtleties of our digital co-authors, stay sharp, stay curious—and drop us a line at Marketing-Ekspercki. We’re always up for a chat about language, style, and what’s next in the world of intelligent content.

Key Takeaways

• ChatGPT and Gemini AI exhibit unique, recognisable writing “idiolects,” much like human writers do.
• Linguistic analysis reveals predictable patterns in vocabulary, phrasing, sentence structure, and tone.
• Recognising and guiding AI style can enhance brand consistency, trust, and content effectiveness.
• Understanding AI idiolects supports content authenticity checks in academia and business alike.
• The next wave? We’ll see even more finely tailored AI voices—each with its own quirks and charms.

For those who geek out over language, or simply want to get the best from their technology, I’d argue there’s never been a more interesting time to pay closer attention to the words we read—and who (or what) might have written them.