national capital vs capital of Italy

national capital and capital of Italy both are nouns.

Word	Noun	Adjective	Verb	Adverb
national capital	Yes	No	No	No
capital of Italy	Yes	No	No	No

national capital (noun)	capital of Italy (noun)
the capital city of a nation	capital and largest city of Italy; on the Tiber; seat of the Roman Catholic Church; formerly the capital of the Roman Republic and the Roman Empire