nuclear physicist vs Gustav Hertz

nuclear physicist and Gustav Hertz both are nouns.

Word	Noun	Adjective	Verb	Adverb
nuclear physicist	Yes	No	No	No
Gustav Hertz	Yes	No	No	No

nuclear physicist (noun)	Gustav Hertz (noun)
a physicist who specializes in nuclear physics	German physicist who with James Franck proved the existence of the stationary energy states postulated by Bohr (1887-1975)