national leader vs Cassius Longinus

national leader and Cassius Longinus both are nouns.

Word	Noun	Adjective	Verb	Adverb
national leader	Yes	No	No	No
Cassius Longinus	Yes	No	No	No

national leader (noun)	Cassius Longinus (noun)
a person who is a respected leader in national or international affairs	prime mover in the conspiracy against Julius Caesar (died in 42 BC)