The term semi-auto and auto mean the same thing in this case. I qualified expert on the 45 in the Navy. I own 2 M1911's.
We finally have something in common.
No it does not. The 45, which I also qualified on, was actually a Model M1911 45 caliber pistol. It used a .45 acp (Automatic Colt Pistol) round. This is a specific weapon and round. A pistol can be an automatic, semi-automatic, revolver or single shot. Shotguns come in single shot, doubles (over under/side by side) semi-automatic and automatic.