There's this weird meme going pedantic circles claiming that "north America has no native buffalo" and that the American buffalo is actually a bison.
That's as stupid as saying, "Actually, a 'chip' is a thick slice of potato, deep fried."
Go to m-w.com and look up buffalo. Across the pond, the definition might be different, but that just makes it different, not wrong. North American bison are buffalo, and to argue otherwise is the worst kind of pedantry: *wrong* pedantry. Stop it.