Differences between processes and threads in Linux and *BSD (i.e. OpenBSD)

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Hello,
I have read blog post about processes and threads. I would like not to post link here, because this is not in English. It basically says that *BSD's processes and threads model at the lower layer are different than in example Linux kernel.
I would like to learn more, but I don't know where to search. I seek for information about differences between these kernels/operating systems, which are practical, pragmatic for somebody who wants to write some userspace programs, which will not be included in base of *BSDs. I would like to use this knowledge in C language.
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Added:
I don't want to mean that I don't actually know conceptual difference between process and thread. I seek differences in these two fields:
1. threads in Linux - threads in *BSDs
2. processes in Linux - processes in *BSDs