Although many people use the two words "guilt" and "shame" interchangeably, from a psychological perspective, they actually refer to different experiences. Guilt and shame sometimes go hand in hand; the same action may give rise to feelings of both shame and guilt, where the former reflects how we feel about ourselves and the latter involves an awareness that our actions have injured someone else. In other words, shame relates to self; guilt to others. I think it's useful to preserve this distinction, even though the dictionary definitions often blur it.
Guilt: a feeling of responsibility or remorse for some offense, crime, wrong, etc., whether real or imagined.
Shame: the painful feeling arising from the consciousness of something dishonorable, improper, ridiculous, etc., done by oneself or another.
According to Dictionary.com, then, guilt involves the awareness of having done something wrong; it arises from our actions (even if it might be one that occurs in fantasy). Shame may result from the awareness of guilt but apparently is not the same thing as guilt. It's a painful feeling about how we appear to others (and to ourselves) and doesn't necessarily depend on our having done anything. I find this a little confusing but an example might help. In the anecdote I related in a post from my website about 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 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 I said before, in everyday language people tend to use these words more or less interchangeably; as a therapist, the distinction I'm trying to clarify is important and useful. Many people crippled by shame 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. The lack of empathy to be found in narcissistic personality disorder makes real guilt unlikely since guilt depends upon the ability to intuit how someone else might feel.
When shame is especially pervasive (what I refer to as core or basic shame), it usually precludes feelings of genuine concern and guilt from developing; the sense of being damaged is so powerful and painful that it crowds out feeling for anyone else. In such cases, idealization often comes into play: other people are then viewed as perfect, the lucky ones who have the ideal shame-free life we crave; powerful envy may be the (unconscious) result. In those cases, we might take pleasure in hurting the person we envy rather than feeling guilty about it. I discussed this dynamic in detail in my post about why we love and hate celebrities.
In other words, core shame reflects early psychological damage that impedes growth; the capacity to feel guilt depends upon that psychological growth and could be seen as emotional progress. If the early environment is "good enough," we develop a reliable sense of self that in turn enables us to view other people as separate and to feel concern for them. Although the experience of guilt is painful, our ability to recognize that our own actions may have hurt someone, to empathize with that person's pain and to feel remorse for having caused it are all signs of emotional health.
A new publication
I've just released a new eBook on the Kindle platform, a novella-length retelling of the classic Cinderella story: Cinderella: A Tale of Narcissism and Self-Harm. The seeds of this story began for me when I asked the question: How would Cinderella actually have turned out if she'd grown up surrounded by people who hated and abused her? Warning: If you have a history of self-injury, you might be triggered by this story. The language is both dramatic and graphic.