To covet is to want somebody else’s good so strongly (‘inordinately,’ as the Christian tradition says) that one is tempted to steal it. To envy is to resent somebody else’s good so much that one is tempted to destroy it. The coveter has empty hands and wants to fill them with somebody else’s goods. The envier has empty hands and therefore wants to empty the hands of the envied.
Cornelius Plantinga, Not the Way It’s Supposed to Be: A Breviary of Sin (Grand Rapids: Eerdmans, 1995), 162.