The difference is that with coroutines, yielding is explicit. Tight-looping will hog the CPU, and a blocking call will block other coroutines too. Typically "gr

The difference is that with coroutines, yielding is explicit. Tight-looping will hog the CPU, and a blocking call will block other coroutines too. Typically "green threads" are semantically just threads but cheaper. They're scheduled independently, so there's no risk of them hogging the CPU, and you can use synchronous apis. The one downside is that you need explicit synchronization between them, whereas with coroutines you can mutate shared data structures and not worry about race conditions as long as you don't yield in between.