Well, my mom and (now) my brother are both addicted to smoking. I don't think that my brother is willing to accept that he's addicted, but it's pretty apparent when he's going on about not having had a smoke for a while and really needing one and all that. I've smoked cigars, as well as weed and I can say that there was a big difference between tobacco and weed. After smoking a cigar, I had this small urge in the back of mind that was more or less saying "that was good, how about you smoke another one" (or something like that, you get my point). But after smoking weed, nothing. Just a thought of "hmm, that was pretty nice."
It's hard to explain the difference between an addictive urge and just simply wanting to do something. An addictive urge is like something that keeps going on in the back of your mind. If I don't have a Coke for more than say, 4 hours straight, I feel like I need another one. I get this anxious feeling, coupled with a craving for Coke. (You know, like when you feel liek you really want something, be it pizza, or some other snack, specifically?)
Depending on the time of day, and how long it's been since I last had a can of Coke, I might even develop a (rather unpleasant) headache, due to not having Coke.
Even when you're fully aware of your addiction, it's not a single bit easier to stop it. And it makes you that much more miserable, because you know you're addicted, but feel like you can't do anything about it.
I know I could quit if I REALLY wanted to. But I don't want to quite that bad. I like the taste of Coke. In fact, even without the addiction aspect, I prefer Coke to pretty much any other drink out there. It's a combination of the carbonated aspect, and the flavor itself.