physicist vs Aleksandr Prokhorov

physicist and Aleksandr Prokhorov both are nouns.

Word	Noun	Adjective	Verb	Adverb
physicist	Yes	No	No	No
Aleksandr Prokhorov	Yes	No	No	No

physicist (noun)	Aleksandr Prokhorov (noun)
a scientist trained in physics	Russian physicist whose research into ways of moving electrons around atoms led to the development of masers and lasers for producing high-intensity radiation (1916-2002)