bird watcher vs zoologist

bird watcher and zoologist both are nouns.

Word	Noun	Adjective	Verb	Adverb
bird watcher	Yes	No	No	No
zoologist	Yes	No	No	No

As nouns, zoologist is a hypernym of bird watcher; that is, zoologist is a word with a broader meaning than bird watcher:

Other hypernyms of bird watcher include animal scientist.

bird watcher (noun)	zoologist (noun)
a person who identifies and studies birds in their natural habitats	a specialist in the branch of biology dealing with animals
a zoologist who studies birds