Comment by ygra

As far as I understand it, it's all the same concept and the difference is mainly where the scheduler is. Raymond Chen also notes that, while an interesting thing to have in the OS in 1996, they aren't really used anymore. And unlike very kernel-tied things like I/O there isn't much sense to use the OS-provided support that's just on one OS anyway; easier to just include your own scheduler, which also avoids the kernel call overhead.