I have to disagree with the exclusivity there, like, as far as I'm aware a brony isn't really necessarily art-based, the fandom is define by someone liking MLP that isn't part of the target demographic. There is art in the brony fandom, but it all stems from the like of the show, it's just like the furry fandom is "a like of anthropormophic art", but as well has fursuits and conventions derived from it. So my idea is that the fandoms are entirely different because they're about different things, furries is about, specifically, anthropormophic art, while bronies is about specifically the show.
So basically I agree with White up until he says that bronies are "just" about the show, a brony is simply a fan of the show, you can like all the anthro art available and still be a brony if you like the show. But I would agree that if you're a brony, like the art of MLP, but don't like other anthro art, then you're not a fan of anthro art you're just a fan of the show and therefore you're a brony but not a furry.