In WWII, BB => States, C => Cities, CV => Battles, DD => Warriors, SS => Fish. With a few exceptions, as some carriers were named for earlier ships rather than battles. I don't know what the new naming pattern(s) will be. It's all rather confused right now. I wish they'd return to naming the subs for fish, but fish don't vote. At least naming SSNs for States keeps traditions alive.
AB
Oddly enough, the Navy's first real deviation with traditional submarine naming was way cool...of course, I refer to the Nautilus.....It couldn't have been anything else....