Shame and guilt are often used interchangeably, but they're not the same. There are people who are prone to guilt, and people who are prone to shame, and there are major psychological differences between the two groups. So what's the difference?
Guilt is an internal emotion. It's the general unpleasantness that you feel when you believe you have done something wrong, regardless of other circumstances. Shame is what you feel when people notice what you're doing, decide it's wrong — or just stupid — and look down on you. While guilt is associated with morality, shame is not. You feel guilt for murdering a nasty money-lender with an ax, at least if you're in a novel by Dostoevsky. Shame is something you can feel for morally-neutral things, like falling down or playing a bad round of charades.
Most people are able to feel both emotions, but there are groups of people who feel one emotion more readily than the other. There are people who tend to feel "guilt-free" shame, and people who tend to feel "shame-free" guilt. And there is a major difference between those two types of people.
You would be better off being friends with a guilt-prone person than a shame-prone person. Trusting someone who is incapable of feeling guilt is a recipe for disaster. For a person to feel shame, they have to be caught; a person who can't bear the feeling of being disgraced in another person's eyes isn't going to be forthcoming with the truth. You might think that shame-prone people would come around faster once they were caught, but you'd be wrong. Guilt is relieved by addressing the problem and asking for forgiveness. Shame makes people withdraw, run away, fly into a rage, or try to change the story. They don't want to own up to the problem and correct it, because their first priority is pretending it never happened in the first place.
If it sounds like the shame-prone are getting a free pass, another study dispels the notion. Shame is about protecting an idealized version of yourself. If that ideal implodes, it can't be rebuilt. You can't make up for a mistake, you can only make yourself over in the wake of one. And a mistake doesn't have to be moral to take you down — any stupid little thing leaves shame-prone people in a tailspin. Shame-prone people therefore, tend to be depressed, anxious, and withdrawn. They're waiting for a mistake, or the publication of a mistake, to torpedo their entire identity. People who feel guilt just need to screw up, do a little leg work to make up for their mistakes, and feel okay again. Sometimes virtue really does pay off.