I can't believe that there has been so much discussion on this..

Call 'em what you WANT, but don't claim to be CORRECT unless you ARE correct....

ALL cuts, on beef, pork, lamb or game animals are basically the same.. Check with a trained BUTCHER, not necessarily Billy Ray Bob Bubba who cuts up deer down the road...

The bigger strips of meat from both right and left of the spine on the OUTSIDE of the animal are called LOIN...Perhaps back loin... Often called Backstrap...

The tenderloin, or filet, is the much smaller strip of meat that is INSIDE the body cavity on both sides of the spine.. Sometimes they are called the "fish"... This is the source for "filet mignon" in beef, or pork or lamb tenderloins, or whatever..

It's as simple as that.. Call them what you want.. You can call a duck a CHICKEN if you want, but that does not make it correct..