The underlying behavior is the same, but the causes are different. They are both classified under Antisocial Personality Disorder, though there has been considerable disagreement over whether they are two distinct disorders or not.

But one, though biology definitely plays a factor in what temperament you are born with - Aspd is more environmental and due to upbringing, whereas psychopathy has a strong biological origin. MRI's have shown their brains are wired differently. Just as MRI scans have shown that people with BPD have smaller but more active amygdilas, which is why they experience emotions more intensely and for longer durations, and subsequently have greater difficulty with regulating their emotions.