metropolis vs Vatican City

metropolis and Vatican City both are nouns.

Word	Noun	Adjective	Verb	Adverb
metropolis	Yes	No	No	No
Vatican City	Yes	No	No	No

metropolis (noun)	Vatican City (noun)
people living in a large densely populated municipality	the capital of the State of the Vatican City
a large and densely populated urban area; may include several independent administrative districts