naturalist vs life scientist

naturalist and life scientist both are nouns.

Word	Noun	Adjective	Verb	Adverb
naturalist	Yes	No	No	No
life scientist	Yes	No	No	No

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

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

Other hypernyms of naturalist include biologist.

naturalist (noun)	life scientist (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