nuclear physicist vs Richard Feynman

nuclear physicist and Richard Feynman both are nouns.

Word	Noun	Adjective	Verb	Adverb
nuclear physicist	Yes	No	No	No
Richard Feynman	Yes	No	No	No

nuclear physicist (noun)	Richard Feynman (noun)
a physicist who specializes in nuclear physics	United States physicist who contributed to the theory of the interaction of photons and electrons (1918-1988)