Borderline Personality Disorder vs. Narcissistic Personality Disorder: How are They Different? Narcissistic personality disorder (NPD) is defined by the Fourth Edition Text Revision of the Diagnostic and Statistical Manual of Mental Disorders. ‘Narcissists are missing that piece about valuing, caring and their relationships, so they tend to lack empathy, they have poor relationship skills. That’s one of the biggest differences, those communal and caring traits tend to be high in…