They are very different. BPD is about having two different psychological integrations operative in one personality: an evolved, mature adult personality alongside a very primitive, infantile, emotional personality.
What makes BPD people unique—what makes them striking—is that they can be incredibly rational and intelligent at a given time, and then two minutes later be completely insane (and also dangerous). This is often wrongly chalked up to their being psychopaths or to their feigning being insane. But it is because someone with BPD involves their having two personalities, a normal one and an infantile one. The infantile one is narcissistic, since that is how infants are. It is utterly self-centered, like an infant, and thus comes off as (and to some extent actually is) psychopathic.
But we’re not dealing with textbook narcissism or psychopathy; we are dealing with narcissism and psychopathy that are subordinate to, and internal to, the infantile half of the BPD person’s personality.