There is no official definition of the difference between a psychopath and a sociopath, and some say that the terms are largely interchangeable. In fact, the The Diagnostic and Statistical Manual of Mental Disorders (DSM) lists both psychopathy and sociopathy under the heading of Antisocial Personalities. Both psychopaths and sociopaths engage in similar actions and tend to have similar characteristics. The idea of psychopathy is older than that of sociopathy, and has a more defined means of diagnosis. Some differentiate between these conditions based on their proposed causes, but others disagree with this method, as the causes of both conditions are not definitively known. Additionally, both of these conditions are generally considered to be different from psychosis and Anti-Social Personality Disorder (ASPD), though these terms are sometimes associated with them.
Both a psychopath and a sociopath have a complete disregard for the feelings and rights of others. This often surfaces by age 15 and may be accompanied by cruelty to animals. These traits are distinct and repetitive, creating a pattern of misbehavior that goes beyond normal adolescent mischief. Both fail to feel remorse or guilt. They appear to lack a conscience and are completely self-serving. They routinely disregard rules, social mores and laws, and don't care about putting themselves or others at risk.
There's a lot of debate about the presentation of a psychopath versus a sociopath. Some people say that a psychopath is extremely well-organized, secretive, and manipulative, while a sociopath is disorganized, unable to pass for "normal," and messier in his or her crimes. Others say the exact opposite. People may try to differentiate between a psychopath and a sociopath based on his or her ability to feel compassion, saying that a psychopath feels no compassion for anyone at all, while a sociopath might feel compassion for his or her family members or friends. There is no consensus on these distinctions, however, and since individual psychopaths and sociopaths have distinct personalities, the behavior of one person diagnosed as one or the other might differ entirely from someone else with a similar diagnosis.
There is no widely accepted set of diagnostic criteria for sociopathy, so it's typically diagnosed using the criteria for psychopathy. Psychopathy is commonly diagnosed using the Hare Psychopathy Checklist - Revised (PCL-R). It is divided into two factors: "aggressive narcissism," and "socially deviant lifestyle." Factor one includes characteristics like a lack of empathy, failure to accept responsibility for one's actions, and an over-inflated sense of self-worth, among other things. Factor two includes things like continuously leeching off of other people, being easily bored and impulsive, and lacking long-term goals. There are other characteristics that don't fit in either factor, like sexual promiscuity and having many short marriages.
There are other proposed models for diagnosing this condition, including the Cooke and Michie model, which contains three axes of behavior — Arrogant and Deceitful Interpersonal Style, Deficient Affective Experience and Impulsive and Irresponsible Behavioural Style. Some people also use the DSM-IV's list of traits for ASPD to diagnose psychopathy. This includes four criteria, including a disregard for other's rights, being at least 18, having a conduct disorder since before being 15, and not having another disorder that can cause the same symptoms. Others disagree with this means of diagnosing, since ASPD is not strictly the same disorder. The character traits associated with both a psychopath and a sociopath also tend to overlap with the DSM-IV's criteria for narcissism and histrionic personality disorder, so tests for these conditions may also be used in diagnosing.
Some separate psychopathy and sociopathy based on their proposed causes. For instance, some people say that a person is a psychopath if he or she developed psychopathic characteristics primarily because of a genetic predisposition, and a sociopath if he or she developed the characteristics primarily in response to environmental factors, like abuse. Others say that they're both just different ways of describing ASPD. This method of differentiating between a psychopath and a sociopath is sometimes criticized, since the causes of psychopathy, sociopathy, and ASPD are not entirely clear, and are likely a combination of genetic and environmental factors.
Psychopathy and Sociopathy versus Psychosis and ASPD
People often confuse the idea of psychosis with psychopathy or sociopathy, or think that all psychopaths are psychotic. These disorders are actually very different, and rarely overlap. Someone who is psychotic tends to lose touch with reality, usually to the point of having hallucinations or delusions. Psychopaths and sociopaths are usually very grounded in reality — they understand what they're doing and the consequences of their actions, but they don't care. A psychopath or a sociopath might kill someone's dog because he or she wans to cause emotional trauma to the owner; someone who is psychotic might kill the dog because he or she thought it was robot sent to take over the world.
Both the DSM and the World Health Organization's (WHO) International Classification of Diseases (ICD) list both terms as synonyms for ASPD, but the terms are generally not interchangeable. ASPD is a much broader diagnosis than psychopathy, and is primarily focused on behavior, rather than characteristics or neurological differences. Though some consider both psychopathy and sociopathy as subtypes of ASPD, others claim that they are very different conditions.