The reds are quite a bit larger. But as far as habits, diet, temperment, etc. go, they act the same and have the same needs. Some people say the blue legs are less aggressive, but that's not true in my experience.
sweet!! thanks a lot. I was debating which one I would get. lol I'm trying to get rid of my "red slime". How many do you think I would need in a 55 gallon? Im thinking of mixing and matching with Astreas as well.
They aren't going to eat red slime, if that's what you want them for. They will kill and eat any snails that you get though. A lot of people don't like hermits in their tanks for that reason.