I'd have to agree with the response that they're really just two facets of Antisocial Personality Disorder. As someone said before, 'psychopath' and 'sociopath' aren't really clinical terms anymore, more like descriptive of patterns of behavior. However, 'psychopath' and 'sociopath' are not interchangeable. You'll know psychopathic behavior when you see it, but you're unlikely to identify sociopathic behavior right away; sociopaths are usually master manipulators, while psychopaths take a more direct approach to causing damage.
At least this is how it's been described to me, coming from a criminal psychology perspective. Hope this helps! :)