Well, when we say someone has a drug habit, and we say someone has a drug addiction - it's *generally* considered one and the same since both "addiction" and "habit" involve the chronic, repeated ingestion of a particular substance.
But, I will admit that you are correct in that someone can technically have a habit to an addictive substance, without actually being addicted to it. It all depends on how frequent the substance is used, and in what quantity. "Clinically" addiction is officially diagnosed if withdrawal symptons present in the absense of the substance.
Most WOD'ers and people in the "drug treatement" industry consider addiction and habituation one and the same.
Personally, I don't care. Addiction, Recreation, Habit ... who cares? It's none of anyone's business. I think people should be able to eat, smoke, and drink whatever they want (not wherever they want - I don't want people having sex in public parks either) - but on their own property, whatever they wish.