Here is a chart showing all of the different styles of karate originating from Okinawa, which any non-karate person would see as more or less exactly the same if they saw them in action.
Underneath it is a chart of different styles of metal. For a non-metal fan (like me), I can just about discern that there is a difference between black metal, which is the kind where the guy shrieks like he is having his testicles mangled in a vice, and death metal, which is the kind where the guy sounds like he is so depressed and angry that he wishes he was having his testicles mangled in a vice. But it turns out that if you are into metal you are usually also really into its cladistics: there are dozens of different ways of screaming and dozens of different kinds of testicle-mangling devices.
(I wish I could find a proper version of this image in a scale which is readable, but you get the point.)
I find this sort of genealogy fascinating. What to one person is hitting and kicking people, playing a guitar really loud and screaming a lot, or pretending to be an elf, to another is a vast and complex field of nuance stretching to each and every horizon and beyond. The particular tiny distinctions between different ways of pretending to be an elf matter.
I want to go out on a limb and say that men - a certain type of man - find this stuff important to a greater degree than women do. For some reason it's more often the case that when somebody is getting uptight about how something is categorised, nine times out of ten it's a man. Why is this? To play armchair anthropologist, is it something to do with a testosterone-driven need to organise and structure the world - to maintain order over complexity? To reduce the confusion, chaos and happenstance of human experience to a set of strictly delineated categories which can then be discussed, compared, critiqued, loved, hated, and (perhaps most importantly) named?