What is ChatGPT? What is Claude? What is a Model?
ChatGPT and Claude are apps you talk to
ChatGPT is a chat app made by a company called OpenAI. Claude is a chat app made by a company called Anthropic. Both let you type a message and get a written reply back — like texting, except you're texting an AI instead of a person.
What a "model" actually is
The "model" is the actual AI brain doing the thinking — GPT-4 or GPT-5 is the model behind ChatGPT; Claude Sonnet or Claude Opus is a model behind Claude. The app (ChatGPT or Claude's website) is just the window you use to talk to the model. Think of the app as the phone, and the model as the person on the other end of the call.
Why there are different versions and names
You'll see names like "GPT-4o", "Claude Sonnet 4.5", or "Claude Opus". These are different models from the same family — newer numbers are usually smarter or faster, and companies release new ones every few months. You don't need to memorize version numbers; just know that picking a newer model usually means better results.
Key Takeaways
- ChatGPT (by OpenAI) and Claude (by Anthropic) are chat apps you use to talk to AI.
- The "model" is the actual AI doing the thinking; the app is just the interface to it.
- Model names and version numbers change often — newer usually means smarter or faster.
- You don't need to memorize model names to use these tools effectively.
Open both apps
Visit chat.openai.com and claude.ai (create free accounts if you haven't). Find where each shows you which model you're currently talking to.