I have unfortunately known both.
Sociopathic people are socially dangerous, and can't quite keep things on solid ground from what I've experienced. It's unfortunate that they have become how they are, but I just try to avoid them. They often seem to have this circle of chaos surrounding them (chaos happens, and sometimes a number of things at one time, but rarely do people have the same chaotic experiences over and over).
The couple of psychopaths I've met scared the hell out of me (and I did not scare easily prior). I never saw it coming until the veils of facade slipped, but once they did slip... I never forgot the true nature of the person. One tipped over the line and has DO designation, and the other has barely managed to hold their facades so to date they've either never gotten caught, or they've never crossed the final line.
Scary stuff!