What is the same
Both are hosted chat UIs from frontier US labs (OpenAI and Anthropic). Both are fine for learning prompting. Both can hallucinate. Both are the wrong place for passwords, unpublished research, or other people’s private data.
Practical differences
Tutorial gravity: More English walkthroughs still say “open ChatGPT.” If you follow random blogs, that reduces friction.
Long notes and checklists: Claude.ai often feels stronger when you drop in long readings or “follow this list” asks. Still verify facts and citations.
Features and plans: Free and paid tiers, file uploads, and project folders change often. Judge the current UI on official sites, not a year-old screenshot.
Try the same three prompts
A: explain a concept you know like you are teaching a friend.
B: make a seven-day plan with real constraints (hours, weak spots).
C: critique your own outline and list missing evidence.
Keep the better answers in your notes, rewritten in your voice.
FAQ
Which is free?
Both offer free-tier access that changes over time. Expect limits. Paid tiers buy higher limits and features, not automatic truth.
Should I start with an API instead?
No. Learn prompting in the browser first. Move to APIs (OpenAI, Anthropic, or a router) when a project needs automation.