Four Trees is the spot where all the gatherings are held, but if StarClan is angry or does not like the discussion the clouds will cover the moon and the gathering is dismissed early.
MoonStone is a large cave with a stone inside, all clan cats at least make 1 journey here in their life-time, this is the only place the clans can really talk to StarClan.
The twoleg nests are the nests that the twolegs live in with their kitty-pets, unless something like catnip is needed most cats never venture this close to the twolegs