Sandwiches and subs are very similar foods, but are ultimately their own things. If you promise a group of people subs and then present them with a bunch of sandwiches they will rightly be perplexed and frustrated as to why you are playing cruel food games with them. On the flipside, if you promise people sandwiches and bring them subs, they will be pleasantly surprised (because subs are inherently superior). Either way, people's perceptions are very, very different with these types of foods despite their many similarities. Maybe the answer is looking at something like linguine vs. udon. Both are noodles, yet both are not pasta. well, both are not italian noodles, which is the cultural definition of pasta. all pasta really means is paste, as in the original form of the noodle. using that definition, all members of the noodle family are paste first, and are therefore all pasta regardless of continent/culture of origin. we just don't consider that a meaningful working definition because of common usage but you're conflating common usage with our very academic food classification discussion. in common usage, you probably would never say "let's go get sandwiches" and drive straight towards your favorite sub shop. but in the academic sense a sub is very much a sandwich (using my definition which is clearly the best). my guess is that the sub predates the sliced-loaf sandwich by many years, if not ages. mapping the familial tree, however, whereby the purest form is the parent and all variations are branches from the main, a submarine is a child of the sliced-bread sandwich; defined by the bread, but different enough that it warrants its own branch. the same goes with the "burger" and its variations, open-faced things like the horseshoe and the hot brown, etc. wraps are not sandwiches, they are gringo burritos and deserve a fate not unlike kim jong un's uncle