I'm no expert but bulimics typically purge on a daily or regular basis. The bingeing and purging anorexics will restrict food but then will have a binge/purge episode every so often (some even plan the day). I think that one is a separate type of anorexia that overlaps bulimia. Like I think it became a new type of disorder on it's own. Most people don't realize that even 20 years ago, there were really only 2 EDs, anorexia and bulimia and now there is a whole range of them.