Saigon vs urban center

Saigon and urban center both are nouns.

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

Saigon (noun)	urban center (noun)
a city in South Vietnam; formerly (as Saigon) it was the capital of French Indochina	a large and densely populated urban area; may include several independent administrative districts