zoology vs oology

zoology and oology both are nouns.

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

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

zoology: the branch of biology that studies animals
oology: the branch of zoology that studies eggs (especially birds' eggs and their size, shape, coloration, and number)

zoology (noun)	oology (noun)
the branch of biology that studies animals	the branch of zoology that studies eggs (especially birds' eggs and their size, shape, coloration, and number)
all the animal life in a particular region or period