Auckland vs metropolis

Auckland and metropolis both are nouns.

Word	Noun	Adjective	Verb	Adverb
Auckland	Yes	No	No	No
metropolis	Yes	No	No	No

Auckland (noun)	metropolis (noun)
the largest city and principal port of New Zealand	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts