biology vs zoology

biology and zoology both are nouns.

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

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

biology (noun)	zoology (noun)
the science that studies living organisms	the branch of biology that studies animals
all the plant and animal life of a particular region	all the animal life in a particular region or period
characteristic life processes and phenomena of living organisms