I'll just state the obvious: A mafia family is one organization, a cartel is a group of organizations involved in one joint venture.

If we are speaking of Central American or North American cartels compared to a mafia family in the States or in Europe, the differences are also going to be determined by the business model. The business model of the C or S American cartels involve farmers and peasants who grow their contraband, likely with government sanction. In contrast, a mafia family might usually be involved in distribution or refinement of that product. To my knowledge mafia families don't have armies of peasants and farmers working for them. The cartels many times are outright land owners and farmers.