nuclear physicist vs Ernest Walton

nuclear physicist and Ernest Walton both are nouns.

Word	Noun	Adjective	Verb	Adverb
nuclear physicist	Yes	No	No	No
Ernest Walton	Yes	No	No	No

nuclear physicist (noun)	Ernest Walton (noun)
a physicist who specializes in nuclear physics	Irish physicist who (with Sir John Cockcroft in 1931) first split an atom (1903-1995)