Chat & Reasoning Models: ChatGPT, Claude, Gemini, Grok, DeepSeek

Slogan: "There's no 'best' AI. There's only the right tool for the asked-for outcome."

The big 5 (mid-2026 snapshot)

1. OpenAI — ChatGPT (GPT-5, GPT-5-Codex, o3)

• Vibe: The all-rounder. Most polished product. Best ecosystem.
• Best at: general chat, brainstorming, image gen (DALL·E 4), voice mode, custom GPTs.
• Reasoning model: o3 and o4-mini — slower, deeper thinking, math and code.
• Weakness: Can sound corporate by default. Token limits in free tier.
• Pricing: Free, Plus ($20), Pro ($200), Team, Enterprise.

2. Anthropic — Claude (Sonnet 4.5, Opus 4.5, Haiku)

• Vibe: The thoughtful colleague. Best writing. Best at long documents.
• Best at: writing prose, coding (especially refactoring), analysis of long docs (up to 1M token context), nuanced reasoning.
• Killer features: Projects, Skills, Artifacts, Computer Use.
• Weakness: Slower to ship multimodal features. No native image gen.
• Pricing: Free, Pro ($20), Max ($100/$200), Team.

3. Google — Gemini (3 Pro, 3 Pro Thinking, Flash)

• Vibe: The infinite-memory analyst. Deeply integrated with Google.
• Best at: massive context (2M tokens — feed it a whole codebase), Google Workspace tasks, multimodal (video + audio + image native), grounded search.
• Killer features: NotebookLM, Deep Research, native Workspace integration.
• Weakness: Personality can feel flat. Some answers play it safe.
• Pricing: Free, AI Pro ($20), AI Ultra ($250).

4. xAI — Grok (Grok 4, Grok 4 Heavy)

• Vibe: The unfiltered one. Real-time X data.
• Best at: current events, X/Twitter trends, less "corporate police" tone, fast image gen.
• Weakness: Less polished, ecosystem still maturing.
• Pricing: Free with X, Premium+ ($16-$30), SuperGrok.

5. DeepSeek, Qwen, Mistral, Llama (open / open-weight)

• Vibe: The hackers' choice. Cheap or free. Run them yourself.
• Best at: coding (DeepSeek-V3, Qwen3-Coder), running locally, building your own products without OpenAI bills.
• Killer features: Open weights — fine-tune on your own data, run on your own hardware.
• Weakness: You're responsible for hosting and safety.

The "which one for what" cheat sheet

How to actually pick (without joining 5 subscriptions)

Most builders rotate 2 tools:

1. One "thinker" for chat, writing, analysis — pick Claude OR ChatGPT OR Gemini.
2. One "builder" for coding — usually Claude Code, Cursor, or Lovable.

Don't subscribe to all five. Pick one of each lane, master it, switch only when you hit a real wall.

The smart workflow: cross-checking

For high-stakes outputs (legal, medical, financial), ask the same question to 2 different models and compare. Disagreements = places to dig deeper.

Funny truth: People used to argue iPhone vs Android. Now they argue Claude vs GPT. In 5 years the kids won't believe we had this debate either.

Learning objectives

By the end of this lesson you should be able to:

• Explain the core idea of Chat & Reasoning Models in your own words to a non-technical friend.
• Recognise where this concept shows up in real projects and tools you already use.
• Apply at least one specific technique from this lesson to something you're building this week.

Practical exercise (10–15 min)

1. Open a new note (Notion, Apple Notes, whatever) titled "Lesson 13.1 — my notes".
2. Write 3 sentences answering: "If I had to teach this lesson to myself yesterday, what are the 3 things I'd absolutely say?"
3. Now do the smallest possible version of it — one prompt, one file, one setting change — and paste the result into your note.
4. Add one honest sentence: "Where I got stuck / what surprised me."

Ship the note to yourself. That's the loop we'll repeat every lesson.

Estimated time

• Reading: ~13 min
• Exercise: ~10–15 min
• Total: ~27 min

Remember: Reading is not learning. The exercise is where the neurons actually wire up.

Deep dive — the long version

You already have the short version above. This section is the hour-long, sit-down version — the kind of walkthrough you'd get from a mentor over coffee. Skim it the first time, then come back and read it slowly once you've done the exercise. That's where the real learning happens.

1. Why this lesson exists at all

Chat & Reasoning Models: ChatGPT, Claude, Gemini, Grok, DeepSeek is one of those topics that seems obvious after you know it and completely opaque before. Almost every learner we've watched trip on this ends up tripping in the same 3 places:

1. They memorise the vocabulary but not the mechanics. They can say the word, but if you ask them to draw what's happening, they freeze.
2. They jump to tools too fast. They pick a framework or an AI product before they understand what problem it actually solves.
3. They confuse "reading" with "learning". Reading gives you recognition. Doing gives you recall. Only recall counts when you're building.

The point of this deep dive is to hit all three of those failure modes head-on, in slow motion, with plenty of examples.

2. A story to anchor the idea

Imagine you're teaching a curious 10-year-old about chat & reasoning models: chatgpt, claude, gemini, grok, deepseek. They don't care about your credentials. They just want a picture in their head that makes sense. Here's the story we'd tell them:

A long time ago, before phones and Wi-Fi, if you wanted to know something you had to walk to the library and ask a librarian. The librarian would find a card in a little wooden drawer, walk to a shelf, pull down a book, and hand it to you. You'd sit at a desk and read it.

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Everything in this lesson is that same story — just with the librarian replaced by a computer, the shelf replaced by a hard drive, and the walk replaced by the internet.

That story is the mental scaffold. Every technical detail you'll learn from here onwards hangs off it.

3. The mechanics, one step at a time

Let's slow the whole thing down. Pretend we're watching a replay in slow motion.

Step 1 — The request. Something (a person, a script, another computer) says "I would like this thing." In a browser, that's typing a URL. In an AI app, that's typing a prompt. In a bank app, that's tapping a button.

Step 2 — The middleman. A layer of software takes the request, tidies it up, and forwards it. In a browser this is called the network stack. In an AI app it's an API client. You almost never see this middleman, but it's always there.

Step 3 — The doer. A computer far away receives the request, does some work (looks something up, generates something, calculates something), and produces a result.

Step 4 — The reply. The result travels back the same way it came. Middleman receives it, tidies it, hands it to whoever asked.

Step 5 — The rendering. Whatever asked for it now shows the result on a screen, plays a sound, or takes an action.

That five-step loop is literally every interaction on every website, every app, every AI tool. Once you can spot the five steps, nothing in tech is truly mysterious again — it's just variations on the loop.

4. Three worked examples (from easy to less easy)

Example A — Reading a news article. Steps: click a link (request) → your browser asks a server (middleman) → the server sends back HTML (doer + reply) → the browser paints text on your screen (rendering).

Example B — Asking ChatGPT for a limerick. Steps: type the prompt (request) → the ChatGPT client bundles it with your session token (middleman) → OpenAI's servers run the model (doer) → text tokens stream back (reply) → the client paints them one word at a time (rendering).

Example C — Ordering food on an app. Steps: tap "order" (request) → the app opens an authenticated connection (middleman) → the restaurant's system receives the order and prints a ticket (doer) → a confirmation comes back (reply) → the app shows "Order placed" and starts a progress bar (rendering).

Different domains, exact same loop. This is why one skill (understanding requests and responses) transfers everywhere.

5. Common mistakes and how to avoid them

• Mistake 1: Skipping the exercise. Reading feels productive but the neurons only wire up when you produce something. Do the exercise. It's 10 minutes.
• Mistake 2: Learning the buzzword first. "What's LLM? What's RAG? What's SSR?" You don't need those words yet. Master the 5-step loop first, then the buzzwords slot in.
• Mistake 3: Comparing yourself to people 2 years ahead. They started too. They also felt lost. The only useful comparison is you today vs you last week.
• Mistake 4: Watching tutorials as entertainment. Tutorials are training wheels, not the destination. If you're not typing along, you're watching TV.
• Mistake 5: Believing "AI will just do it". AI is a very fast intern with amnesia. If you can't describe what you want in plain sentences, no model on earth will get you to a good result.

6. A checklist you can actually use

Before you leave this lesson, tick these off honestly:

• [ ] I can explain chat & reasoning models: chatgpt, claude, gemini, grok, deepseek in 3 sentences without notes.
• [ ] I can point at something in real life that uses this idea.
• [ ] I finished the practical exercise, not just read it.
• [ ] I wrote 1 question I still don't know the answer to.
• [ ] I know which lesson comes next (see the "Next up" card at the bottom of the page).

If any of those are unticked, don't move on. Loop back and close them. The learners who ship are the ones who don't skip.

7. Where this lesson connects

Every future chapter will assume you internalised this idea. Specifically:

• *When we talk about prompts*** — a prompt is a request in step 1.
• *When we talk about tools*** — a tool is a specialised doer in step 3.
• *When we talk about building your own product*** — you're going to design your own version of the loop, end to end.

That's why we made you sit through the story. Everything else in the handbook is a variation on it.

8. Bonus: three questions to journal on

If you want to really lock this in, spend 5 minutes writing (not typing — actually writing) answers to these:

1. What part of chat & reasoning models: chatgpt, claude, gemini, grok, deepseek was I secretly avoiding thinking about?
2. If I had to teach this to my past self one year ago, what would I say first?
3. What is the smallest possible project I could build this week that uses this idea?

Those three prompts, repeated across every lesson in the handbook, are the single highest-leverage habit we've seen in learners who go from zero to shipping in under 6 months.

Next up

If this lesson clicked, keep the momentum going — hit the Next → card at the bottom of this page. If you struggled, do this instead:

1. Re-read sections 3 and 5 slowly.
2. Redo the practical exercise from scratch.
3. Re-read your notes again in 24 hours. Sleep genuinely helps memory consolidate — it's not folk wisdom, it's biology.

Progress is not a straight line. Circling back is how mastery is built.