greed vs cupidity

greed and cupidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
greed	Yes	No	No	No
cupidity	Yes	No	No	No

As nouns, cupidity is a hyponym of greed; that is, cupidity is a word with a more specific, narrower meaning than greed:

greed: excessive desire to acquire or possess more (especially more material wealth) than one needs or deserves
cupidity: extreme greed for material wealth

Other hyponyms of greed include avarice, avariciousness, covetousness, possessiveness, acquisitiveness.

greed (noun)	cupidity (noun)
reprehensible acquisitiveness; insatiable desire for wealth (personified as one of the deadly sins)	extreme greed for material wealth
excessive desire to acquire or possess more (especially more material wealth) than one needs or deserves