Formal breeds often considered in North America to be of the pit bull type include the American Pit Bull Terrier, American Staffordshire Terrier, American Bully, and Staffordshire Bull Terrier. Pit bull is the common name for a type of dogs with similar physical characteristics, and the morphological (physical) variation amongst "bully breed" dogs makes it difficult for anyone, even experts, to visually identify them as distinct from "non-pit bulls".
