Older Colt revolvers in .45 Colt had bore diameters of .454" while .45 ACP had a bore diameter of .451". Of late both use .451" diameter.
To answer your question, .45 ACP bullets can be used in .45 Colt cartridges. The heavier cast lead SWC bullets intended for the .45 Colt usually do not work too well in ACP cartridges.
I have loaded the 230 gr Hornady jacketed Flat Point bullet in the .45 Colt and in .45 S & W cartridges to good results.