What, exactly, is the difference between sociopathy and psychopathy?
I believe there are some minor differences, for example, WebMD Article states:

A key difference between a psychopath and a sociopath is whether he has a conscience, the little voice inside that lets us know when we’re doing something wrong, says L. Michael Tompkins, EdD. He's a psychologist at the Sacramento County Mental Health Treatment Center.
A psychopath doesn’t have a conscience. If he lies to you so he can steal your money, he won’t feel any moral qualms, though he may pretend to. He may observe others and then act the way they do so he’s not “found out,” Tompkins says.
A sociopath typically has a conscience, but it’s weak. He may know that taking your money is wrong, and he might feel some guilt or remorse, but that won’t stop his behavior.

Also, I've read somewhere (I believe it was Theodore Millon's book) that psychopathy is more about nature and sociopathy is more about nurture. In other words, psychopaths are born the way they are, while sociopaths acquire severe trauma that makes them the way they are.
This also goes along nicely with psychopaths being more calm and able to manipulate, while sociopaths are more impulsive and irritable.