Monterrey vs metropolis

Monterrey and metropolis both are nouns.

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

Monterrey (noun)	metropolis (noun)
an industrial city in northeastern Mexico	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts