Clear differences exist between those who lie pathologically and those who lie compulsively. The two conditions are often confused with one another or seen as interchangeable, but, importantly, there are significant differences in motivation and practice. Compulsive liars and pathological liars both lie frequently, but they do so for different reasons and pose different problems for those with whom they have contact.
Pathological liars lie with what might be called “intent”. They have a clear purpose or aim they hope to achieve through lying. They can be manipulative and cunning and normally care little for the opinions or feelings of others. Pathological liars simply want things their own way.
A compulsive liar is someone who has little or no control over the lies he or she tells. Lying, for them, is habitual and constant. They may lie about anything and in any situation. They lie to avoid the truth, perhaps because they find telling the truth uncomfortable.
It appears that low self-esteem is a significant factor in the development of a compulsive liar. The condition may be developed whilst in childhood and in most cases, compulsive liars are relatively harmless. They lie habitually and may be aware of doing so, but find themselves unable to stop.
Pathological liars create an alternate reality for themselves to inhabit. They believe in their lies and become unable to separate their lies from the truth. This means they have no problem lying brazenly about apparent episodes in their lives in order to gain favour or admiration. Their stories may change over time and they may act defensively when confronted.
On the other hand, compulsive liars have little or no motive for lying. They lie simply because they cannot help but do so or because they find the truth uncomfortable. Unlike pathological liars, they do not have a particular goal in mind when lying.
Certain psychological conditions may also affect the type of liar a person may be or become. For instance, those who suffer from Anti-Social Personality Disorder or Narcissistic Personality Disorder may be pathological liars, while compulsive liars can occasionally be sufferers of ADHD, Bipolar Disorder or Borderline Personality Disorder. It must also be pointed out that a compulsive liar may not in fact suffer from any mental disorder.
As for treatment, these conditions can only be properly addressed after an admission on the part of the sufferer. Professional help should be sought and help from those in contact with the sufferer - personally and professionally - will have a bearing on the success or failure of the treatment.