operating systems – Do the software threads include user threads?

I want to know if the software subprocesses include user threads. For user threads I mean in the
Subprocess model n-1, that part "n" is for user threads. I read an answer that says that the software threads are threads managed by the operating system, but then the threads of the users are managed by the thread library, so that they are not software subprocesses. I also received a response from the chat, where people say that the software sub-processes have a different level. I'm very confused.