Pisa vs urban center

Pisa and urban center both are nouns.

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

Pisa (noun)	urban center (noun)
a city in Tuscany; site of the famous Leaning Tower	a large and densely populated urban area; may include several independent administrative districts