Whoops. The bullet is the same. The cartridges are different lengths and charge/pressures differ greatly. A .380 is a 9mm short (and used to be called that). Not a good idea to shoot a 9mm in a .380 due to pressure ratings..380 ACP, .380 Auto, 9mm Browning, 9mm Corto, 9mm Kurz, 9mm Short, 9×17mm and 9mm Browning Court are all the exact same cartridge.