So whats the difference from buying the game and downloading it from the marketplace?

Sorry if this question has been asked alot.

I don't care about the campaign, so if I download the maps from the marketplace am I getting the full H1 multiplayer experience?
Or
Does the disc have some multiplayer h1 stuff that I won't receive unless I buy disc?

The game comes with a code. The code == the maps on the marketplace. The only thing you get with the game is the game. No H1 multiplayer etc