Great questions! Might be very different, however, due to different publication forms and habits in the humanities than in the sciences (books vs. articles, single-author vs. multi-author etc.).
I don't doubt that there are differences. However, my understanding is that the peer review system was adopted as a standard in the sciences first, biomed sciences in particular. It then spread elsewhere to the sciences, and finally to the humanities. Do you think this is along the right lines?