English bulldog and British bulldog are two names for the same breed of dog, which is properly called a bulldog, so there is no difference between them. According to Bulldogs World, some people use the "English" or "British" qualification to help the uninitiated differentiate between bulldogs and other bulls, such as mastiffs and terriers.
The National Kennel Association recognizes the American bulldog as a separate breed, and there are differences between it and the English bulldog. Daily Puppy notes that American bulldogs are taller and more muscular. English bulldogs average 40 to 50 pounds, while American bulldogs weigh in at 85 to 105 pounds. Also, American bulldogs have longer legs and sleeker builds. It should be noted that the American Kennel Club does not consider the American bulldog to be a distinct breed.
Bulldogs were originally bred in England as farm animals, and they were used in a vicious sport called bullbaiting in which dogs bit down on bulls' noses and shook them. Although bullbaiting was thought to improve the bulls' meat, it became as much a source of entertainment as a farm tool. Bulldogs' physical characteristics, such as body width, muscularity and strong jaws, combined with bred-in aggressiveness, made them an ideal choice for this brutal practice.
Modern bulldog breeders focus on temperament. Following an 1835 ban on bullbaiting, notes DogTime, breeders stopped breeding aggressive dogs and selected only gentle animals instead. As a result, today's bulldogs have a reputation for being friendly, gentle and affectionate animals. However, the distinct physical characteristics bred into bulldogs remains relatively unaltered. As a result, bulldogs suffer a range of health problems.