Are there "types" of stutter?

Are there "types" of stutter? I've known a couple of people who have stuttered, but neither of them have stuttered like I do. I don't often have trouble with vowels, but usually I'll go 'sssssss', 'fffffffffff' or 'shhhhhhhh'. I also have quite a lot of trouble with d, t, and g, but I use a lot of fillers like 'um' to make those easier. I used to be a lot worse, but I've noticed that some people seem to have the same 'type' of stutter as me, but others stutter on different sounds. How do you guys stutter?