If I play a Xbox360 recreation on-line on a Xbox Collection s, who do I play with then?

I wish to get a Xbox Collection S to play some outdated Name of Obligation video games. I don't even know, if these video games are nonetheless performed, however I had one other query in thoughts. If I play for instance Black ops 2 on-line on my Collection S, do I simply get folks, who additionally play black ops 2 on a Collection S/X? Or do I additionally get individuals who play black ops 2 on a Xbox one and Xbox360? I used to be simply questioning and to know. Possibly somebody will help me.