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.