Bombay vs urban center

Bombay and urban center both are nouns.

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

Bombay (noun)	urban center (noun)
a city in western India just off the coast of the Arabian Sea; India's 2nd largest city (after Calcutta); has the only natural deep-water harbor in western India	a large and densely populated urban area; may include several independent administrative districts