urban center vs Portsmouth

urban center and Portsmouth both are nouns.

Word	Noun	Adjective	Verb	Adverb
urban center	Yes	No	No	No
Portsmouth	Yes	No	No	No

urban center (noun)	Portsmouth (noun)
a large and densely populated urban area; may include several independent administrative districts	a port town in southeastern New Hampshire on the Atlantic Ocean
	a port city in southern England on the English Channel; Britain's major naval base
	a port city in southeastern Virginia on the Elizabeth River opposite Norfolk; naval base; shipyards