What is the difference between coveting and stealing?
Coveting is wanting to possess what another person has. A similar word to "coveting" is "greed." "For the wicked boasts of his heart's desire, and the greedy man curses and spurns the LORD" (Psalms 10:3). In other words, a covetous man is selfish. Other people do not matter. The only thing that matters is what I want.
Coveting can be a motivation behind stealing, but a person might take what belongs to another for other reasons. A person might steal bread because he is hungry or because he gets a thrill from doing something dangerous. A man might kidnap a person to get revenge against another. Kidnapping is a form of stealing.
At the same time, coveting can be the motivation behind other crimes. A person might commit adultery because he wants another man's wife. Another person might slander a popular politician because he thinks he should be the one the crowds should follow. In a sense, covetousness is a form of idolatry. "Therefore consider the members of your earthly body as dead to immorality, impurity, passion, evil desire, and greed, which amounts to idolatry" (Colossians 3:5). The covetous man’s god is himself. He worships his own desires and sees himself as the center of the universe. Everything must bow before his desires.