One of the main differences between the two is that OCD is ego-dystonic, whereas OCPD is ego-dystonic. This means that in OCD (an anxiety disorder) the sufferer realizes that something is unnatural about the way that they are behaving. It is consciously bothersome. In OCPD (a personality disorder), the sufferer sees it as part of his/her personality and it really doesn't feel unnatural or "wrong" (for lack of a better term-- I really hate to use the words "right" or "wrong" in describing things). Anyway, OCPD sufferes are very unlikely to come into treatment by their own accord because they really just see it as an extension of themselves.