There is no official body which draws a distinction between problem drinker and alcoholic. All you will get here is a bunch of opinions.
I don't know why you are asking the question but I have seen this debate raged on in this forum many a time. I don't think it ends up being helpful because ultimately no one is right or everyone is right.
I think a better thing to do is ask yourself or ask us why you are asking the question. Is it because you are wondering if you are really an alcoholic? Then maybe you should read specifically about the symptoms of alcoholism or the feelings that typical alcoholics have towards alcohol or read CarolD's post.
I just think it is difficult because if people put up here that problem drinkers aren't alcoholics and they don't have problems and then you end up deciding you identify as such and you no longer have a problem, it is very hard to know whether it is the addict voice that has convinced you of that or not.
I don't know— I guess I just feel like it is every alcoholic's dream to consider themselves a "problem drinker" and to define problem drinker as someone who drinks maybe a little too much but isn't an alcoholic. Oh wait, I thought I was a problem drinker for seven years. Awesome.