naturalist vs biologist

naturalist and biologist both are nouns.

Word	Noun	Adjective	Verb	Adverb
naturalist	Yes	No	No	No
biologist	Yes	No	No	No

As nouns, biologist is a hypernym of naturalist; that is, biologist is a word with a broader meaning than naturalist:

naturalist: a biologist knowledgeable about natural history (especially botany and zoology)
biologist: (biology) a scientist who studies living organisms

Other hypernyms of naturalist include life scientist.

naturalist (noun)	biologist (noun)
a biologist knowledgeable about natural history (especially botany and zoology)	(biology) a scientist who studies living organisms
an advocate of the doctrine that the world can be understood in scientific terms