AP Fan

Essentially, a true fan is someone that is enthusiastic about all of your work. They follow you closely and purchase anything and everything you produce. A fan, according to the American Heritage College Dictionary, is "an ardent devotee, an enthusiast." Fanatic is defined as "a person marked by an extreme unreasoning enthusiasm, as for a cause." The distinction, then, apparently rests on whether the enthusiasm is ardent or unreasoning.