San Sebastian vs urban center

San Sebastian and urban center both are nouns.

Word	Noun	Adjective	Verb	Adverb
San Sebastian	Yes	No	No	No
urban center	Yes	No	No	No

San Sebastian (noun)	urban center (noun)
a city in northern Spain on the Bay of Biscay near the French border; a fashionable seaside resort	a large and densely populated urban area; may include several independent administrative districts