Seven Hills of Rome vs Italian capital

Seven Hills of Rome and Italian capital both are nouns.

Word	Noun	Adjective	Verb	Adverb
Seven Hills of Rome	Yes	No	No	No
Italian capital	Yes	No	No	No

Seven Hills of Rome (noun)	Italian capital (noun)
the hills on which the ancient city of Rome was built	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