Bronies are fans of a particular fictional universe,and the things they do are often bound by thst universes rules. Brony as a whole could fit into a subcategory of Furry, but there's a lot of stigma associated with both, so they tend to not associate, citing the other's "cringe" examples. Speaking freely, Brony, the basic part of it at least, is a bit closer to beastality. The characters are closer to ferals in form, but still posses cognitive capability, which is really where the line is drawn for beastality. With furry, they are not as close to the line due to many of the animal species being "adapted" into a more human form- As you could see the canine had the general human outline, was bipedal, human hands and such instead of paws....and also includes the female secondary sex characteristic that is more human than canine.