San Antonio vs urban center

San Antonio and urban center both are nouns.

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

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