Karachi vs urban center

Karachi and urban center both are nouns.

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

Karachi (noun)	urban center (noun)
the largest city in Pakistan; located in southeastern Pakistan; an industrial center and seaport on the Arabian Sea; former capital of Pakistan	a large and densely populated urban area; may include several independent administrative districts