Nicholas, succinct and to the point....I like it!
And here is the Russian folk tale ( a bit apropos for one named after a Czar) : There were two farmers in the Ukraine. Ivan had fallen on hard times and lost all his sheep, while Peter still had a flock of twelve. One night an angel appeared to Ivan to grant him one wish. He thought long and hard about Peter's sheep. He could either wish for 12 sheep like Peter possessed (jealousy) or he could choose to have Peter's sheep disappear forever (envy). So, this is how I prefer to interpret the difference...one is pure desire of another's possession, the other, so intense, as to desire the other's misfortune.