Another article, about envy, from the Stanford Encyclopedia of Philosphy has a small section explaining the difference between jealousy and envy:
D'Arms, Justin, "Envy", The Stanford Encyclopedia of Philosophy (Spring 2009 Edition), Edward N. Zalta (ed.),
URL = <http://plato.stanford.edu/archives/s.../entries/envy/>.
"1.2 Envy vs. Jealousy
Ordinary language tends to conflate envy and jealousy. The philosophical consensus is that these are distinct emotions. While it is linguistically acceptable to say that one is jealous upon hearing about another's vacation, say, it has been plausibly argued that one is feeling envy, if either, in such a case. Both envy and jealousy are three-place relations; but this superficial similarity conceals an important difference. Jealousy involves three parties, the subject, the rival, and the beloved; and the jealous person's real locus of concern is the beloved—the person whose affection he is losing or fears losing—not his rival. Whereas envy is a two party relation, with a third relatum that is a good (albeit a good that could be a particular person's affections); and the envious person's locus of concern is the rival. Hence, even if the good that the rival has is the affection of another person, there is a difference between envy and jealousy. Roughly, for the jealous person the rival is fungible and the beloved is not fungible. So he would be equally bothered if the beloved were consorting with someone else, and would not be bothered if the rival were. Whereas in envy it is the other way around. Because envy is centrally focused on competition with the rival, the subject might well be equally bothered if the rival were consorting with a different (appealing) person, but would not be bothered if the ‘good’ had gone to someone else (with whom the subject was not in competition). Whatever the ordinary meaning of the terms ‘envy’ and ‘jealousy,’ these considerations demonstrate that these two distinct syndromes need to be distinguished."
Note: I had to look up the definition of fungible
ˈfʌndʒəbəl [fuhn-juh-buhl] –adjective (Law). (esp. of goods) being of such nature or kind as to be freely exchangeable or replaceable, in whole or in part, for another of like nature or kind.