Oh er... I think they are the same. In my opinion, the difference of being "envious of someone" and being "jealous of someone" is just in the degree in discontent or resentment I would feel.
If I am envious of someone, maybe its just resentful of someone for having something I don't have. Being jealous of someone may mean I have stronger feelings of resentment than just envy.
In most cases, it should be safe to say they can be used interchangeably. If I want to express myself in a same sentence, I could say," I am envious of his great wealth, and jealous of his ability to make money so easily." Even if you change the words around, it wouldn't change the meaning.