national leader vs Duke of Wellington

national leader and Duke of Wellington both are nouns.

Word	Noun	Adjective	Verb	Adverb
national leader	Yes	No	No	No
Duke of Wellington	Yes	No	No	No

national leader (noun)	Duke of Wellington (noun)
a person who is a respected leader in national or international affairs	British general and statesman; he defeated Napoleon at Waterloo; subsequently served as Prime Minister (1769-1852)