Fun fact, what you call async is also widely referred to as coroutines. Stackless coroutines vs stackful coroutines seems like the most appropriate way to disambiguate the two.
Before async for I/O became popular, stackless coroutines were mainly used for generator abstractions (for example yield in python), so async can be reductive.
And that's exactly why I would say "async", because then everyone will know that I'm talking about something like async in Python/C#, and not something like Python generators.
Technically, they're may well be almost the same thing, but practically, they're used very differently.
