Sao Louis vs metropolis

Sao Louis and metropolis both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sao Louis	Yes	No	No	No
metropolis	Yes	No	No	No

Sao Louis (noun)	metropolis (noun)
a city on an offshore island in northeast Brazil	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts