Edit-add Another idea is to separate one particular head stamp for use in the 38 acp and not load it for the super at all. You can only shoot factory or your reloads that way with that brand of brass. OR you could use brass cases for acp and nickle for super.

If you can find an old box of 38 acp ammo at a gun show you might use them or you could take a file and put a notch on the rim or use paint in the head stamp or extractor groove to make the gun-specific brass identifiable. There are LOTS of options to choose from

As for the new-guy question... it's complicated...(to explain in a word or two, if you haven't been around guns & ammo much)... you would get a lot more answers by starting a new thread with a descriptive title.