You may have heard people call someone else a “psychopath” or a “sociopath.” But what do those words really mean? You won’t find the definitions in mental health’s official handbook, the Diagnostic and Statistical Manual of Mental Disorders. Doctors don’t officially diagnose people as psychopaths or sociopaths. They use a different term instead: antisocial personality disorder. Most experts believe psychopaths and sociopaths share a similar set of traits. People like this have a poor inner sense of right and wrong. They also can’t seem to understand or share another person’s feelings. But there are some differences, too.

Do They Have a Conscience? 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. Both lack empathy, the ability to stand in someone else’s shoes and understand how they feel. But a psychopath has less regard for others, says Aaron Kipnis, PhD, author of The Midas Complex. Someone with this personality type sees others as objects he can use for his own benefit.