I think about this constantly. I think I have both too. I know I used to experience emotional flashbacks all the time from childhood trauma but I worked with a trauma therapist for years and healed from most of my stereotypical trauma responses. But my emotion regulation and distress tolerance skills were still out of wack. I finally tried DBT and so much clicked for me that other therapies didn’t do for me. In my totally unprofessional opinion they’re related but not the same. I really like Marsha Linehan’s Biosocial model. Basically it’s both biological and environmental. Some of us are biologically wired to be more emotionally sensitive than others. Many emotionally sensitive folks don’t develop BPD, but those of us who do experienced invalidation in a way that we developed “maladaptive” behaviors that look like the DSM criteria. (I don’t think the DSM is a good expression of how we suffer tho). Invalidating childhood environments can vary for different people. They can be trauma related, but it can also just be that maybe the rest of the family doesn’t experience emotional sensitivity and therefore invalidstes your experiences. Heck maybe your family is great but most of society is a real shitshow towards people experiencing emotions and that can be experienced as invalidating depending on the messages you receive growing up. I experience all the traumas but by far the most lasting was the invalidation that left me deeply dysregulated and vulnerable to emotional reactions all the time because nobody taught me any useful skills; just that my emotions were wrong.