Mannheim vs metropolis

Mannheim and metropolis both are nouns.

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

Mannheim (noun)	metropolis (noun)
a city in southwestern Germany at the confluence of the Rhine and Neckar rivers	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts