No, the difference is, at least from what I've seen (am not sure if the research supports this, but it would be interesting if it did not), some people (like myself) seem to be more susceptible to smoking addiction than others. I know quite a few people who have no trouble smoking intermittently, with months in between, and then quitting with hardly any effort. Maybe they just have more resolve or willpower, but I've seen them smoke more than enough to "catch" the addiction like I did, then stop, never really getting stuck into a daily habit. Yes I'm jealous :) On the other hand, I don't want to smoke just "occasionally" either, I just want to quit.