As to ASPD i was under the impression it is synonymous with psychopathology.
The two terms seem to be very ill-defined in the literature. According to my experience, psychopathy pretty much means a lack of emotion, especially negative emotion, and including moral emotion; and impulsivity. All the recognised cluster-B personality disorders also suffer from impulsivity. You sometimes get people with narcissism and aspd with psychopathic traits like a lack of fear or conscience.
Even though narcissists are highly emotional, you sometimes get cold-hearted people with a competitive nature, leading me to think there’s a crossover between narcissism and psychopathy.
Cluster B personality disorders include narcissism, borderline, anti-social and histrionic (“drama queen” people).
According to what I’ve read, the most dangerous combination is Borderline + ASPD, because they can’t handle their emotions, and feel entitled to take it out on others.