historian vs Publius Cornelius Tacitus

historian and Publius Cornelius Tacitus both are nouns.

Word	Noun	Adjective	Verb	Adverb
historian	Yes	No	No	No
Publius Cornelius Tacitus	Yes	No	No	No

historian (noun)	Publius Cornelius Tacitus (noun)
a person who is an authority on history and who studies it and writes about it	Roman historian who wrote major works on the history of the Roman Empire (56-120)