avifauna vs zoology

avifauna and zoology both are nouns.

Word	Noun	Adjective	Verb	Adverb
avifauna	Yes	No	No	No
zoology	Yes	No	No	No

As nouns, zoology is a hypernym of avifauna; that is, zoology is a word with a broader meaning than avifauna:

Other hypernyms of avifauna include fauna.

avifauna (noun)	zoology (noun)
the birds of a particular region or period	the branch of biology that studies animals
	all the animal life in a particular region or period