Model vs. tool vs. app

These words get used interchangeably. They're not the same.

• A model is the underlying brain — like *GPT-5* or *Claude Sonnet 4.5*. You don't usually interact with it directly.
• An app is the product wrapped around a model — *ChatGPT*, *Claude.ai*, the *Gemini* app.
• A tool is a capability the model can use inside an app — web search, image generation, code execution, file analysis.

You drive the app. The app uses a model. The model reaches for tools when it needs them.