All four of these run on the same basic idea from Lesson 1 — trained on huge amounts of text, predicting good-sounding answers. The differences come from who built them, what they trained them to prioritize, and what they've bolted on around the core model. Here's the honest rundown.
| Tool | Made by | Personality | Best known for |
|---|---|---|---|
| ChatGPT | OpenAI | Fast, eager, list-shaped answers. The one that made all of this famous. | The biggest ecosystem — plugins, custom GPTs, voice mode, image generation, huge user base. |
| Claude | Anthropic | Careful, conversational, writes in sentences that sound like a thoughtful person. | Long documents, long-form writing that needs less editing, holding context across a big conversation. |
| Gemini | Direct, well-integrated, sometimes chatty. | Living inside Gmail, Docs, and Sheets — if your life already runs on Google, this one's already half set up. | |
| Perplexity | Perplexity AI | Terse and citation-first — behaves more like a research assistant than a conversationalist. | Questions where you want sources you can click and verify, not just an answer to trust blind. |
The honest bottom line
None of these is "the best AI" — that framing doesn't hold up. They're four well-funded companies converging on similar technology with different personalities and different things they're plugged into. Most people who use AI seriously end up with a primary tool (usually whichever fits how they already work) and reach for a second one occasionally for its specific strength — Perplexity when they need a citation, Gemini when they're already inside a Google Doc.
You'll also see model names inside each tool — GPT-5, Claude Sonnet, Gemini Pro, and so on. Think of these like engine trims within a car brand: newer usually means smarter and pricier. Don't chase the newest name. A free-tier model, used well, will outperform the fanciest model used carelessly — and prompting well is what the rest of this site teaches.
Which one is "yours" for this course?
Prompt Queen AI's paid Level 1 courses cover Claude and ChatGPT specifically, because between them they cover the vast majority of what small-business owners and creators actually need. Gemini and Perplexity are genuinely good tools, but if you're starting from zero, picking one of the first two and going deep beats spreading yourself across all four.
If you already have accounts anywhere, open two of these tools side by side and ask both the exact same question — something real, not a test question. Notice the difference in tone and length before you judge which answer is "better." That felt difference is most of what separates them.