There's a lot of overlap and confusion when it comes to triceps movements. Most of the terms have multiple meanings and are just confusing. Best to stick with the term extensions and forgo the use of either french press or skulls, because in both cases there are multiple interpretations of what they are and/or the exercises aren't nearly as effective.
French press is a confusing term because you'll see all sorts of interpretations as to what it means-sitting, lying, where to lower the weight, etc. The definition in this thread for example is only one of the interpretations i've seen over the years, so don't even get bogged down trying to make sense of it or use that term.
Skulls are another confusing term that is sometimes mixed with extensions. Skulls shouldn't even be bothered with, they're not a terribly effective exercise while being hard on the elbows and dangerous if the weight's dropped. I see this exercise done all the time and consider it quite a waste of effort.
Do all versions of extensions behind the head, whether sitting, lying or with overhead pulley. Far more effective, and depending on the angles and exercise, easier on the joints.
What's amazing to me is that even some pros don't understand the advantages of one over the other, whereas others do. Without a doubt the ones doing extensions behind the head are the more informed ones-Larry Scott, Yates and Boyer Coe for example.
