Uuuugh fine. A "Brony" is someone who is a fan of My Little Pony Friendship is Magic but does not fall under the (original) target demographic. They're essentially adults and teens who like my little pony. A "Furry" could mean a lot of things. The most generic and harmless definition I can give is someone who associates themselves with an animal. But it can get much much deeper than that, and it usually does.