enthusiasm vs avidity

enthusiasm and avidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
enthusiasm	Yes	No	No	No
avidity	Yes	No	No	No

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

Other hyponyms of enthusiasm include gusto, relish, zest, zestfulness, avidness, eagerness, keenness, exuberance, technophilia.

enthusiasm (noun)	avidity (noun)
overflowing with eager enjoyment or approval	a positive feeling of wanting to push ahead with something
a lively interest
a feeling of excitement