The Psychopathic Personality functions in society and is often quite successful. In fact many CEOs have a Psychopathic Personality.
However the Psychopathic Personality Disorder is a psychosis, and the sufferer is psychotic. And they do suffer because they are unable to function in society because they are out of touch with reality.
So on one hand we have a personality and on the other we have a psychosis. Unfortunately they have similar names and so they are often confused.