A psychopath is a person who has a high score on the checklist. If you get a 40 for example then you are a psychopath. If you get a 40 and the neuroscience backs it up via brain scans then you are a clinical psychopath.
We all might have some of the traits and tendencies but it's a matter of degrees. Also a psychopath isn't capable of experiencing certain emotional states ever in life.