We do not suggest substituting pork loin for pork tenderloin as these are two different cuts of meat that come from different areas of the animal. Pork loin is a wide slab of meat and can be bone-in and bone-out, whereas pork tenderloin is boneless, long, and some may say, tube-shaped. The cook times and methods vary between the two types of meat and should not be substituted for one another.