Roma vs national capital

Roma and national capital both are nouns.

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

Roma (noun)	national capital (noun)
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	the capital city of a nation
a member of a people with dark skin and hair who speak Romany and who traditionally live by seasonal work and fortunetelling; they are believed to have originated in northern India but now are living on all continents (but mostly in Europe, North Africa, and North America)