POSIX Threads vs. Win32 Threads
There are huge differences between how threads are managed and scheduled "under the hood" in Windows NT family kernels and on many Unix kernels, but that's not the question.
If you're just talking about the interface (the services exposed by Win32 threads and POSIX threads), with some work you can almost map any POSIX thread feature to a Win32 equivalent ~1:1. And it has been done (see pthreads-win32).
One big difference I may notice is that under Win32 you use actual system calls to work with threads, instead POSIX threads' calls are part of a library (pthreads), that - under many Unix systems - calls some very low level system calls of Unix kernels (under Linux there's clone()).
Just to prove you that, unless you go very deep, pthreads is nothing so special, you can download pthreads-win32 that exposes quite the same interface of pthreads, and any function is mapped on Win32 thread APIs. And it works.
One small but crucial difference seems to be that there's no POSIX equivalent to Windows's CREATE_SUSPENDED.