Envy: sinful lusting after something which belongs to someone else. Covetousness.
Jealousy: righteous indignation toward someone who lusts after something that is yours.
Often we misuse these two words. We use envy when we really mean jealous and we say jealous when we really mean envy. These two words are not interchangeable. To envy is to commit sin; to be jealous is righteous.
A biblical example of envy is found in I Kings chapter 21 where King Ahab lusted after the vineyard of Naboth. King Ahab and his wife, Jezebel, plotted and had Naboth killed so that Ahab could take the vineyard. 1 Kings 21:5-7 says,
5 But Jezebel his wife came to him, and said unto him, Why is thy spirit so sad, that thou eatest no bread?
6 And he said unto her, Because I spake unto Naboth the Jezreelite, and said unto him, Give me thy vineyard for money; or else, if it please thee, I will give thee another vineyard for it: and he answered, I will not give thee my vineyard.
7 And Jezebel his wife said unto him, Dost thou now govern the kingdom of Israel? arise, and eat bread, and let thine heart be merry: I will give thee the vineyard of Naboth the Jezreelite.
You see, envy is the same as covetousness. The tenth commandment reads thusly: Exodus 20:17, "Thou shalt not covet thy neighbour's house, thou shalt not covet thy neighbour's wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbour's."
Jealousy is what you feel when someone makes a pass at your spouse. A biblical example of the proper use of the term "jealousy" is found in Exodus 34:13-15:
13 But ye shall destroy their altars, break their images, and cut down their groves:
14 For thou shalt worship no other god: for the LORD, whose name is Jealous, is a jealous God:
15 Lest thou make a covenant with the inhabitants of the land, and they go a whoring after their gods , and do sacrifice unto their gods, and one call thee, and thou eat of his sacrifice;
Take heed, a frequent misuse of the word Jealous is when a person will grill his marriage partner thusly: "Where have you been?" "Who were you with?" "Who did you see?" Additionally, the person will make false accusations: "Don't lie to me!" "Give me the car keys, you cheater!" "It doesn't take that long to go to the beauty shop!" "Had to get prettied up for your boyfriend didn't you!"
Then the accused spouse will accuse him of being jealous, but this is not jealousy, this is insecurity. If the accused marriage partner has a history of infidelity then the insecurity may be justified, but frequently the insecurity is simply based on unfounded suspicion. This insecurity may be caused by the accuser having witnessed the infidelity of others close to him and maybe even his own infidelities.
This type of insecurity sometimes responds well to pastoral counseling, but if there is physical abuse because of imagined infidelity then this is a serious mental condition that usually does not respond to any kind of counseling.