The Tenderloins are the small strips of meat on the inside cavity or back bone down toward the hips. The Backstrap or Loins or Rib Eyes are the two large strips of meat running down the outside of the backbone. The Filet Mignot are the two medium strips on the inside of the backbone up in the rib cage. Here is a simple butchering page.
http://www.wideworldofhunting.com/cutsforbutchering.htm#E
Eric S. Stacy