The difference is that it doesn't play well with large parts of the existing Python ecosystem. Concurrency is a pain if you are writing a library or trying to integrate with existing code. Python async is powerful, but:

(1) it's undersupported (e.g. you can in theory download s3 files using async botocore, but in practice it is hard to use because of strict botocore version dependencies)

(2) it isn't natural - once you're in the event loop it makes sense, but using an event loop alongside normal python code is confusing at best.

(3) it got introduced too late. The best async primitives are only available in pretty recent versions of python3.

The difference with go is that it go has these primitives built in from the beginning and using them doesn't introduce interoperability problems.