Canadian Bacon is meat cut from the back of the boneless loin, often lean with little fat and pre-cooked when store-bought.
American Bacon is identified by the USDA as “the cured belly of the swine” — it’s the combination of meat and fat from the belly of the pig, which gives it the streaky look that you see.
English Bacon is cut from the loin back of the pig, similar to that of Canadian but with the added fat surrounding the meat. English bacon is often smoked or cured, again similar to that of Canadian, but to a greater extent. Bacon in the UK also comes in a form similar to American, but is actually referred to as “streaky bacon” and is less common.