.45 Auto vs .45 ACP

[TheBigCroaker]

Being new to 45's, could someone tell me what the difference is (if any) between ammo marked ".45 Auto" and that marked ".45 ACP."
Are they identical? Can either be used in a Glock 21.
I would definitive answers, not opinions, please
Thank You.

[HGun17]

http://en.wikipedia.org/wiki/.45_ACP

They are the same.

[TheBigCroaker]

Thanks HGUN

[vafish]

.45 ACP , ACP=Automatic Colt Pistol Same thing as .45 Auto.

Just don't get .45 GAP or .45 Colt they are different things.