There is definitely some overlap clinically but I think it's pretty clean-cut diagnostically. There was a time when I questioned my BD diagnosis a lot, and at one point was insisting it was BPD even though that didn't make a lot of sense. My therapist laughed a lot when I told her, and said no, not at all. Doctor said the same. Said everyone is a little bit axis 2 sometimes, but that it was not what was going on. In hindsight my goal of telling them that and insisting was because I didn't want to be on/need medication.