national capital vs Vienna

national capital and Vienna both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
Vienna	Yes	No	No	No

national capital (noun)	Vienna (noun)
the capital city of a nation	the capital and largest city of Austria; located on the Danube in northeastern Austria; was the home of Beethoven and Brahms and Haydn and Mozart and Schubert and Strauss