Northampton vs metropolis

Northampton and metropolis both are nouns.

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

Northampton (noun)	metropolis (noun)
the principal city of Northamptonshire	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts