Envy and Jealousy
In his collection of essays on the Seven Deadly Sins, Joseph Epstein singles out envy as the most painful of those sins to experience, with none of the ancillary pleasures that go along with, say, lust or gluttony. As I've discussed elsewhere, nobody wants to feel envious or to acknowledge feeling that way to others. Like hatred in our culture, it remains a taboo subject. It might be acceptable to admit you feel "jealous" that a friend has a trip planned to Europe or bought an expensive new pair of shoes; there's a good chance you could one day go on such a trip yourself or add to your own wardrobe.  Jealousy, in this modern sense, means: "I admire what you have and wish I could have something just like it, too." Jealousy is the cleaned up, socially-acceptable version of envy.
Almost nobody would say, "I'm envious that you're better-looking than I am." You can't change the way you or the other person looks. Few people would admit, "I'm envious that you have a spouse and children while I haven't had a relationship in years." To admit to such feelings acknowledges a level of hatred most personal relationships can't tolerate. For the truth is that envy, the green-eyed monster, wants to destroy what it cannot have. The "solution" to envy -- the way to find relief from the suffering it causes if you can't have what you envy for yourself -- is to make the envied object less worthy of that emotion, by spoiling or destroying it. Aesop's fable about the fox and the grapes speaks of unbearable desire but also describes a psychic mechanism (spoiling) active when envy comes into play.