Although a ribeye steak and a prime rib are both cut from the same rib section of the beef, they do have some differences. The ribeye is cut from between the 6th and 12th ribs, which is considered to be the most tender part of the ribs. It's also more heavily marbled. The other big difference in taste and tenderness is a cut of prime rib is cut off of a cooked roast, whereas ribeyes are individual cuts seasoned and cooked to order.