Located on the lower part of the belly, these have more fat, and there is sometimes a layer of fat on top. The fat adds flavor when they cook, and there’s more tenderness. Spare ribs have a skirt on the back. You can leave it on or cut it off and cook separately.
Baby back ribs
These come from high on the back side of the hog and are closest to the tenderloin. Being close to the loin means they’re leaner. Baby backs usually have 13 bones to a rack. Depending on how they’ve been cut, they are usually smaller and take less time to cook than spare ribs.
St. Louis-style ribs
This is a full rack of spare ribs with the tips cut off. Underneath is a flap of meat called the skirt, which is trimmed off. You can cook the tips and the flap separately. Once those two pieces are trimmed off, the rack is usually trimmed to 12 bones to allow for more even cooking.