You don't have to fit all the criteria for BPD, just a certain number I think (5? Not sure)

Could be wrong on this also but I think with BPD the disturbance to self identity is not as clear cut. With DID my alters and I are very clear on who is who. I am me and they are them, and there is no question about that. (Although with our front group that is merging it is not longer clear cut like that... but it did begin that way.) My experience of DID in me is that I am always me. 'I' am never one of the alts. They each are always themselves, and never someone else. Our identities and sense of self are very clear to us. Our front group has merged somewhat , but even now I am very aware of behaviors or traits that used to belong to another alter and I can clearly identify them within me.