Earlier quoted context omitted.
Beach volleyball is played typically with 2's or 4's. The rules are slightly different, court size is smaller. There are no positions in 2's, there are no position faults. Feel free to make analogies between two other similar sports, such as Competition Karate and Taekwon-Do.
I'm sorry but this still sounds like the same game to me. Why is it not called Beach 2-by-2-ball, or somethign similar, if the number of players makes it so very different? If I get a couple of my mates together and we bounce a ball over a net counting points when the ball hits the ground- how is what we're playing not (an informal game of) volleybal?
I mean, we can talk about things that make things similar all day, it doesn't make them the same thing. Is a hamburger a sandwich? Sometimes, the whole is greater than the parts, not everything is perfectly decomposable in life.