Audio. I know a Showa is a black body with red and white colors on it, and a Sanke is a white bodied fish with red and black. Is that right? To me they look very similar sometimes. How do you tell the difference? I would have guessed that both your new fish were Sankes.
I'm no expert on the rules and I think that body color explanation is an oversimplification--though I am unclear. However, after having seen photos/videos of hundreds of them I seem to guess right most of the time.