Actually they are an ad agency. Their core business is to create advertisements for their customers. It may sound weird when you read it like this, but on the other hand it's not that uncommon: Google is also an ad agency. So the right point to make here is that their pseudo-magazines are for the most part intended as an outlet for their ads. This is all what I have been told anyway, by a buddy who had a job at one of their European branches.
I would say its more a case of, Google is a search company who's revenue model is advertising, while Vice is an online magazine who's revenue model is advertising. Neither of them actually create the ads, they sell space to display them.
