Actually, there is a vast difference between sociopathy and psychopathy. For starters, psychopathy is on a different pathological taxon from sociopathy and its related Axis II, Cluster B disorders. Secondly, there is a measured neurophysiological difference. Moreover, while personal gain may be a motivator, unlike aspd & sociopathy, it is not required. And finally, there appears to be genetic difference as well.
To better understand why this distinction is important, let's first take a look at the Axis II, Cluster B taxon, specifically, antisocial personality disorder (aspd). By its very definition, these people purposefully violate sociolegal norms, often for personal gain. People dx'd with aspd will more likely than not have a history of criminal misconduct that began in their early teenage years. In other words, were either dx'd w/conduct disorder as a juvenile or had plenty of markers indicating that they met the criteria for conduct disorder as a juvenile.
Those w/sociopathic tendencies on the other hand aren't necessarily as blatant as their aspd kinfolk. While these type also violate sociolegal norms for personal gain, they have begun to fine tune their behavior such that they are much more likely to avoid detection and/or arrest. Unlike psychopathy however both aspd & sociopathy have underlying motivators that involve personal gain which in turn, trumps empathy. In other words, these people engage in a process of rationalization and objectification that allows them obviate whatever guilt they may feel as it pertains to hurting others.
Which brings us to the taxonal pathology that people (esp talking heads) seem to toss about with wild abandon when discussing criminal behaviors as they pertain to high profile crimes: psychopathy.
For starters, neurophysiological research indicates a significant correlation between psychopathy and elevated dopamine, noreprinephrine, & testosterone levels, while showing low serotonin levels. Furthermore, unlike the aspd & sociopathy, these types can go undetected for years. In other words, those who score high on Hare's PCL-R have mastered the art of being very engaging, likeable, and trustworthy, while having no real emotional connection with people.
These are the type that few, if any would suspect of engaging in petty, much less egregious, criminal behavior. Two of the most well-known examples are Ted Bundy & Jeffrey Dahmer. Recall, the former was able to lure his victims using the "broken arm" ruse, whereas the latter was able to convince LE to hand his victim over. In other words, the common characteristic for those who fall under the psychopathy taxon is that no one saw them coming.
How is it then, that psychopaths are able to move about, so seemingly invisible? That is, unless they strike? To explain this, Hervley Cleckly makes an interesting analogy in his book, "The Mask of Sanity," by generalizing psychopathy to Henry Head's 1926 term "Semantic Aphasia." Others have gone on to fine tune that analogy with the definition, "they know the words but not the music." In other words, unlike your wannabe psychopaths (i.e., antisocial and/or sociopathic types), these guys are the real thing. They're your true chameleons who may (or not) prey upon an unsuspecting public.
Moreover, contrary to popular opinion, not all psychopaths are killers, nor do they all engage in illegal behaviors, or do nasty, mean, but perfectly legal things to others. In other words, psychopaths who do not engage in behaviors that can be even remotely considered illegal and/or offensive, are referred to as ambulatory psychopaths.
This distinction bears itself out when considering the "Macdonald Triad" (i.e., enuresis, firesetting, & torturing small animals) to predict aspd, sociopathy, & psychopathy. Although this triad was coined in the mid 1960s, it has yet to live up to its hype. Why might that be? Simple. Unlike aspd & sociopathy, psychopathy does not require a history of aberrant and/or sadistic social behavior. Nor does it require a motivator. Therefore, by indiscriminately glomming all three of them (i.e., aspd, sociopathy, & psychopathy) together you end up with extremely poor predictive results that fail in the validity and reliability dept.
And finally, as Hare so noted in his book, "Without Conscience," psychopaths hail from all social strata and environs. Again, unlike aspd & sociopathy, which appear to include reactive behaviors as they pertain to environmental factors, a psychopath can come from a leave it to beaver home life with no indication of bullying and/or other abusive relationships while growing up. This is where the genetic bit may come into play. And though it has yet to be proven, geneticists believe psychopathic predisposition is due to a missing key genetic component that allows society at large to coexist in a meaningful and fulfilling way with each other: empathy.
IMO, it's not necessarily about placing blame as much as it is trying to understand and get into the mind of someone like Casey and understand their behavior.
