physicist vs Klaus Fuchs

physicist and Klaus Fuchs both are nouns.

Word	Noun	Adjective	Verb	Adverb
physicist	Yes	No	No	No
Klaus Fuchs	Yes	No	No	No

physicist (noun)	Klaus Fuchs (noun)
a scientist trained in physics	British physicist who was born in Germany and fled Nazi persecution; in the 1940s he passed secret information to the USSR about the development of the atom bomb in the United States (1911-1988)