nuclear physicist vs Leo Szilard

nuclear physicist and Leo Szilard both are nouns.

Word	Noun	Adjective	Verb	Adverb
nuclear physicist	Yes	No	No	No
Leo Szilard	Yes	No	No	No

nuclear physicist (noun)	Leo Szilard (noun)
a physicist who specializes in nuclear physics	United States physicist and molecular biologist who helped develop the first atom bomb and later opposed the use of all nuclear weapons (1898-1964)