Frank,
The large primers are a little over .210" typical diameter. Small primers are a little over .175" typical diameter, so it's pretty obvious which one you have when you look.
The small primer cases are from NT (non-toxic) ammunition. This is ammunition that uses diazodinitrophenol (DDNP) instead of lead styphnate as the impact sensitizer and bullets whose jackets completely surround the lead core. The idea is to get all the lead vapor out of the air. The problem is the DDNP is a more violent explosive than lead styphnate so it tends to push a large primer out much harder than lead styphnate does, so, to prevent primer piercing they use the harder-to-distort small primer cup and, usually, a larger vent (flash hole). You can
read about it here, if you are curious.
If you want one powder that will run all loads for you in .45 ACP, Bullseye is the old standby. Run 200 grain cast bullets over about 4.5 grains for practice, and run 200 to 230 grain jacketed bullets over 5.0 grains for something closer to full power. I like the Hornady 230 grain TC bullets for that, but anything that isn't round nose you want to double-check for consistent reliable functioning.