Well, they can only get the features of an animal, not entirely. They'd look like weird humanoids or something...

Without saying that I actually know, I don't think so. Else they would have been called the same. I think that a metamorphmagus can only change different features about themselves. They might be able to make all their features look like an animal, but I imagine that there would stille be some human features to them. This is just guess work, I honestly don't know if I'm right.