Great thread and a good question. I don't think there is any "right" answer other than to agree with what many on this thread have already commented. Its like asking what's the difference between a heavy drinker and an alcoholic? I'm not sure. The heavy drinker could very well be an alcoholic and just doesn't want to admit it, and a self described alcoholic might just be a little uptight about drinking, if that makes any sense.
In the end I know that I have flirted with disaster with alcohol which is why I found this site and have maintained a membership. I wish you the very best.