Differences between BPD and CPTSD

What would be some differences between someone with CPTSD and someone with BPD? I ask because I feel like my ex-girlfriend has BPD, she feels like she does as well, so does are mutual friend but her therapist told her she thinks it’s CPTSD. We’re not arguing with the therapist and she’s accepting the diagnosis but just out of curiosity, I wanted to post here. I’ve spent a lot of time reading through threads in this community and I’m amazed at the similarities from other’s experiences and mine.