IME, one of execution. Copilot is like having your cousin who works at Bestbuy try and help you code - it knows what a computer is, and speaks english, but is pretty bad at both

The story I've heard is that Cursor is making all their money on context management and prompting, to help smooth over the gap between "you know what I meant" and getting the underlying model to "know what you meant"

I haven't had as much experience with Claude or Claude Code to speak to those, but my colleagues speak of them highly