Italian capital vs Italia

Italian capital and Italia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Italian capital	Yes	No	No	No
Italia	Yes	No	No	No

Italian capital (noun)	Italia (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	a republic in southern Europe on the Italian Peninsula; was the core of the Roman Republic and the Roman Empire between the 4th century BC and the 5th century AD