How do Mac OS X processes and threads differ?

Question

In my Mac OS X Activity monitor it lists each "process" id for each application. It links several processes to a single thread, for instance iTunes and Finder are currently both listed under thread 7. The way I learned about threads and processes would lead me to think that this should be the other way around. I learned that a process has one or several threads. Can somebody try to clear this up for me. Would these processes they are talking about be considered light-weight processes?

Answer 1

I'm not a OS X user, but from screenshots found by our nice friend Mr. Google it seems that this indicates the number of threads created by that process. So both iTunes and Finder are running 7 threads each.