jealousy vs green-eyed monster

jealousy and green-eyed monster both are nouns.

Word	Noun	Adjective	Verb	Adverb
jealousy	Yes	No	No	No
green-eyed monster	Yes	No	No	No

As nouns, jealousy and green-eyed monster are synonyms defined as:

jealousy and green-eyed monster: a feeling of jealous envy (especially of a rival)

jealousy (noun)	green-eyed monster (noun)
zealous vigilance	a feeling of jealous envy (especially of a rival)
a feeling of jealous envy (especially of a rival)