Deno originally was not Node compatible at all, and required you to do everything in a Deno way:

- Deno plugin in editor, otherwise types dont work

- All imports via absolute URL, like Golang

- No backwards compatibility, so no existing code worked.

Since Deno 2, they've taken Node compatibility much more seriously, hence the 50% to 70% compatibility jump claimed here.

Bun on the other hand, tried to make things Just Work without requiring any thinking for Nodejs / TypeScript developers. It's basically the `node` development experience with all incidental frictions removed (but some segfaults added).

tl;dr: you can use `bun` to write node projects, but `deno` can only be used for deno projects