There are actually two breeds of bulldog that are recognized by the American Kennel Club (AKC): the bulldog, and the French bulldog. The term "English bulldog" probably comes from the breed's country of origin. Both bulldogs of today are most likely very different from the breed's ancestor, as some of the breed's original, undesirable traits were bred out.
It is thought, according to the Bulldog Information Library, that the bulldog originated in the British Isles. The dog was bred for the once popular sport of "bull-baiting," which involved the dog's seizing of the bull by the nose and holding on. Some historians also believe that bulldogs were used in dog fighting. These original bulldogs were bred to have a very fierce temperament in order to fulfill their purpose. Once the two sports were made illegal, breeders had to modify the temperament of the breed.
The AKC weight standard for French bulldogs is 28 lbs. or less. Unlike the bulldog, the French bulldog has a "curious and interested" demeanor. This is the more active and alert of the two breeds. When placed side by side, the French will appear to be leaner than the bulldog. Aside from a more compact build, the other feature that distinguishes the French from the bulldog is the "bat ears," that stand erect and wide.
The Bulldog has a stockier appearance than the French variation. AKC defines the demeanor to be one of "great stability, vigor, and strength." This breed's weight can range from 40 to 50 lbs. to meet AKC standards. The ears of the bulldog are different from the "bat ears" of the French, in that they have a folded appearance. The bulldog's bottom teeth may also be visible when its mouth is closed.
Today both breeds are classified as "non-working" dogs by AKC. Both are considered to be wonderful family pets, due to their fierce loyalty. Today's bulldogs are not typically vicious or temperamental. This is a sharp contrast to the original "English bulldog" that was vicious and even quoted by AKC to be "intolerant to pain."