[Lukasa]

It is not categorically different.

As I said above, green threading has advantages over OS threading, but they behave exactly the same in terms of design patterns and potential bugs.

This is what I was getting at when I said "not that different": compared to the difference between event-loop concurrency and threaded concurrency, M:N green threading is basically just a subcategory of threading.

[sagichmal]

No. Green threads enable entirely new classes of design patterns that are categorically infeasible with OS threads.