You bring up a good point. Where I grew up for part A of my childhood, it was a hoagie. For part B, it was a grinder. First time we ever heard “grinder” my siblings and I looked at each other with those adolescent WTF looks on our faces. Priceless.
Philly. As for grinder, I haven't a clue. Hoagie = Philly, Hero = NY, Po Boy = New Orleans.
However, I think I've stumbled upon a paradox here. Per the USN, the New Orleans is a surface ship. However, New Orleans = Po Boy = Hoagie = Submarine. And, submarine = boat. Oh, I'm so confused...