mind explaining what hg push/pull do to a git only user?

perhaps it's that i'm just only used to git's definitions of the words, but they seem symmetrical to me in the sense that they both try to synchronise history, either upwards or downwards.

i can't really imagine what a pull would do differently than a merge or rebase that would satisfy the idea of synchronisation but be more symmetrical as you describe. i'd really appreciate an elaboration.