urban center vs San Antonio

urban center and San Antonio both are nouns.

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

urban center (noun)	San Antonio (noun)
a large and densely populated urban area; may include several independent administrative districts	a city of south central Texas; site of the Alamo; site of several military bases and a popular haven for vacationers