Pork butt either refers to the roast cut of meat from the front shoulder of the pig, or to ham or roast from the hind leg of a pig or hog. Ham can be sold cured, fresh, or smoked, and can also come from the shank, or lower, end of the pig's leg.
The shank end of a ham comes from the lower portion of the pig's leg. The shank half of a ham is usually bigger than the butt half, with more meat, and has a tapered shape. The shank end is easier to carve because it has less tissue connecting the meat to the bone. Some butchers and chefs prefer the shank end of ham, believing the butt end has more gristle and fat.
The butt end of a ham is smaller than the shank end, and the meat is leaner. Because the bone in this portion of the ham has an irregular shape, it is harder to carve. Some cooks prefer the butt end, believing it has a meatier taste.
Pork shoulder roasts are cut from the shoulder portion of the pig's foreleg, which butchers call the butt. Shoulder arm roasts are prepared from the shank portion of the foreleg, and include part of the shank bone. Both types of roasts are typically sold as "pork shoulder" and may be barbecued or roasted.