Boneless Hind ¼ Primals
1) Eye of Round
2) Bottom Round
3) Top Sirloin
4) Top Round
5) Sirloin Tip
6) Tenderloins
7) Backstraps
Boneless Front ¼ Primals
8) Neck
9) Shoulder
10) Top Blade
11) Mock Tender
Notice the difference between #6 and #7. The smaller ones are the tenderloins (found on the inside) the larger ones are the backstrap (found on the outside). see, i can find web sites too.
Seriously though, as a butcher for many years i understand where the cuts come from