The Difference Between Shame and Guilt
According to Wikipedia, the "dividing line between the concepts of shame, guilt and embarrassment is not fully standardized." Many people use guilt and shame interchangeably, but from a psychological perspective, they actually refer to different experiences.  Quoting from Wikipedia:
"Psychoanalyst Helen B. Lewis argued that 'The experience of shame is directly about the self, which is the focus of evaluation. In guilt, the self is not the central object of negative evaluation, but rather the thing done is the focus.'Â Similarly, Fossum and Mason say in their book Facing Shame that 'While guilt is a painful feeling of regret and responsibility for one's actions, shame is a painful feeling about oneself as a person.'"
I would go further and say that the action that inspires guilt usually involves the infliction of pain, either intentionally or unintentionally, upon another person. As an example, in the anecdote I related in my post on envy and jealousy, I once said something hurtful at a dinner party, and on some level, I intended it to be hurtful. Afterward, I felt guilty about my actions because I could see that I had hurt my friend. More painfully, I also felt ashamed that I was the sort of person who would behave that way. Guilt arose as a result of inflicting pain on somebody else; I felt shame in relation to myself.
As a therapist, I find this distinction to be important and useful. Many deeply troubled people have very little capacity to feel guilt, for example. In order to feel guilt about the harm you may have done to somebody else, you must recognize him or her as a distinct individual, to begin with. Thus a person who struggles with separation and merger issues might not feel true guilt even if he or she were to use that word to describe a feeling. Many people who display narcissistic behavior often suffer from profound feelings of shame but have little authentic concern for other people; they don't tend to feel genuinely guilty. This explains why an authentic sense of guilt rarely appears in narcissistic personality disorder and anti-social personality disorder: guilt depends upon the ability to intuit how someone else might feel and as a result to experience remorse for the pain one has caused.