No, I don't think there's anything fundamentally different.
Ruby 3.0 implements a "fiber scheduler" feature that enables "colorless Async". Fiber scheduler is an obscure Ruby feature, but the end result is brilliant. It was also a huge amount of work.
Side note: Fiber scheduler was implemented by the same guy who created Async Ruby - Samuel Williams. This guy is the mastermind (and master-coder) behind this project.
Ruby async seems to be implemented using stackful coroutines. IIRC Guido has been opposed to adding these to core Python, preferring stack-less coroutines because they require every yield-point to be explicit (i.e. marked with `await`).
There are libraries for a python that support stackful coroutines, such as gevent.
And I think I've come to the conclusion that any re-usable code I write for IO should just be written async with magic sync wrappers for use in sync contexts.