To what extent should morality be re-enforced by the way that we think about or treat people who violate it's tenets?
Shame is typically considered the more primitive method of enforcing morality. Same categorizes the sinner according to the sin committed and applies some sort of punishment as a result. The examples that most readily spring to mind, for me, come from to miniseries based on classic literature that we recently watched with the kids.
In Bleak House, Lady Deadlock is terrified of the shame that will come upon her and her husband if it is ever discovered that prior to her marriage she had a child by another man. When the secret does look like coming out, she runs away in at attempt to shield them from the shame which she thinks must inevitably fall upon her. In Middlemarch, the somewhat less sympathetic Mr. Bulstrode, who has made himself unpleasant around town with his non-conformist moralizing, is in his own turn utterly shamed when it comes out that he got his money dishonestly (and then contributed to the death through negligence of the person who could reveal his past). She is shunned by everyone but his every-loyal wife and has to leave town.
Shame involves tarring the sinner's whole person with the brush of the sin. According to a shame-based way of looking at things, Lady Deadlock is not "a woman who had a child out of wedlock" but "a fallen woman", the sin defines the person and subsumes it. Shame is a powerful way of socially enforcing moral norms because it places a very heavy penalty upon the violation of certain norms. However, it is also an approach which leaves no room for redemption. Shame are a morality-enforcement mechanism sacrifices permanently certain identified sinners in order to serve as an example to others. In this sense it is a predatory means of social enforcement. The only way it can operate is by putting some people beyond redemption, making examples of them that others may not follow in their footsteps. This heavy threat does provide a strong reason not to violate the norms enforced by means of shame, but since the means of enforcement is public, it also creates a strong reason for secrecy. Thus, in both literary examples, Lady Deadlock and Mr. Bulstrode are willing to do almost anything in order to prevent their transgressions from becoming known, since shame only comes into play if the sin is known. Sin that is not known, if avoiding shame is the only way in which people think of sin, is no sin at all.
Guilt is a somewhat more complex approach to moral enforcement. If we think of shame as the idea that people who do certain things are unworthy of being associated with, guilt is the idea that certain actions are unworthy of us. According to guilt, if you commit a sin, you should feel bad about having done so. When morality is socially enforced by means of guilt, there may still be strong social sanctions placed upon someone who violates society's moral norms, but the sinner can redeem himself in the eyes of society by repenting of his sin. But more importantly, guilt is not primarily an external force, it is an internal force. Using guilt, society teaches us that we should blame ourselves if we violate certain norms. This enforcement thus operates whether the sin is known by others or not.
Because the terms are often used in a casual sense, I think they often get mixed up. We often hear people talk about the need to bring back shame -- that people should feel ashamed for doing certain actions. However, half the time what is meant is guilt rather than shame. Guilt is the personal belief, "That action was not worthy of me and I should never do such a thing again." Shame in the sense that I am speaking of here, however, is externally applied -- except perhaps in some sort of despair in which the sinner classifies himself according to the sin he has committed and rejects himself permanently as a result, holding that he will always be defined by that sin and so it hardly matters what he does from here on out.
At the end of the day, it perhaps doesn't matter much how we use the terms. But I don't bring up the matter to make an argument about correct use of terminology, but rather because I think that as those of us who adhere to traditional morality make the case for returning to a clearer sense of sin in society, it's important that we think about the traditional behaviors that we seek to bring back. A sense of guilt can be a very healthy thing, but shame in the predatory sense is not, even though one often saw it used in Christian cultures. Shame in the sense described here leaves no room for redemption, and redemption is, after all, the central message of Christianity.