Although they sound similar, they are quite different cuts of meat and cannot be substituted for one another. Pork loin, technically called pork loin roast, is a much thicker cut of meat that is best cooked low and slow in order to become tender. Usually between 3-5 pounds, it is often sliced and sold as pork chops. Pork tenderloin is a much thinner cut of meat that is best cooked quickly with higher heat for a shorter amount of time. Each tenderloin is usually between 1-2 pounds. It is considered the filet mignon of pork for it's tenderness.