Despite the big differences in the size of baby back ribs and spare ribs, they’re really just two different pieces of the same slab of meat. Baby back ribs (bottom of photo) are cut from the top of the rib cage, near the backbone. Spare ribs (top of photo) are cut from the bottom of the rib cage and sometimes they include the brisket, which is a bony piece of meat that hangs from the bottom. The farther down the rib cage you go, the meatier the ribs become. That is essentially why spare ribs take longer to cook.