Everyone lies from time to time. Studies show that we lie several times a day, for example, "No, ur dress looks nice!" but actually u think she looks like a drag queen. Well, this is just very minor lie, if were to compare with compulsive lying.
I believe a compulsive liar regards telling lies as a routine. It becomes second nature. They not only bend the truth about issues big or small, they take comfort in it. They feel good telling lies, whether to cover their mistakes, delusions, to confuse people, or merely just to cover the lies he/she told before. Because when u tell a lie, u gotta tell more lies to cover the previous lie so that people won't find out the loophole of your 'beautiful' lie.
To deal with a compulsive liar is quite tricky. Getting them to admit they having such problem is difficult. Sadly enough, when counseling and therapy(meditational or spiritual) don't work, it's really up to themselves to come to a realization one day and hope they would come out from this "comfort zone" of lying, face the world and the truth, with sincere heart.