I honestly don't know much about either past my attempts at using them, meaning their actual names, specs, etc. I've used the actual tablets that are separate from the screen and the ones that allow you to draw directly on the screen as well. Call me traditional in my approach, but I could not for the life of me get used to it. Mind you, I can use photoshop, indesign, etc. One thing that really bugged me was the size. I felt extremely restricted.
Most of the students love them though. I seem to be the minority. Thankfully I am free to continue making a mess in my studio however I wish. :D