people use it as an umbrella term but a pitbull is actually an american pitbull terrier. the correct umbrella term would be a bully breed and for a pitbull it would be ‘terrier’. its sort of like if you called all herding dogs [GSDs, border collies, corgis, aussies, etc] “border collies”. hope that makes sense!
But I believe the term "bully breed" covers all bully breeds (muscular body, broad head, short coat, etc...), whereas pit bull covers a select few of these bully breeds, such as the American Pit Bull Terrier, American Staffordshire Terrier, American Bully, etc... American Pit Bull Terrier or Pit Bull Terrier as most call the breed is the name for it, and though many people call the breed pit bulls, it isn't their technical name. "Pit Bull is a description for a type of dog, but American Pit Bull Terriers are a breed."
I guess some/a lot of people call their APBTs pit bulls, but that isn't the correct term.