The difference: The american bulldog 22 - 28 inches and 80 - 140 pounds. The american pit bull terrier 17 - 23 inches and 22 - 65 pounds. ( Some Very rare can reach 80 pounds, but any over 80 is a mix ) American bulldogs, are calm indoors, and outdoors there active, energetic, agile, but then there still great with kids and people they know. American bulldogs, are considerd the second strongest dog breed, are considerd the number one working dog, and the number 6 dog for kids. American bulldogs have the weight pull record of 11,300 pounds or something close. American bulldogs also make a better guard. Dont get me wrong their both great guards and dogs. The Johnson american bulldog looks like a boxer on steroids. And the scott american bulldog looks like an american pit bull terrier on steroids. The boxer is the number 17 dog in strength, the american pit bull terrier is the 18 strongest. They both have amazing body power and jaw power. No dogs jaws lock. The american bulldogs got the apbt beat in muscle by a bit. Also they were bred for different things. The american bulldog was bred for fighting bulls. They also used them to hunt boars and wolfs. Then they used them for dog fighting. The american Pit bull terrier was used to control bull, but also bred to fight other dogs. Then they started using them to hunt boar aswell.