national leader vs Sir Robert Walpole

national leader and Sir Robert Walpole both are nouns.

Word	Noun	Adjective	Verb	Adverb
national leader	Yes	No	No	No
Sir Robert Walpole	Yes	No	No	No

national leader (noun)	Sir Robert Walpole (noun)
a person who is a respected leader in national or international affairs	Englishman and Whig statesman who (under George I) was effectively the first British prime minister (1676-1745)