Kolkata vs urban center

Kolkata and urban center both are nouns.

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

Kolkata (noun)	urban center (noun)
the largest city in India and one of the largest cities in the world; located in eastern India; suffers from poverty and overcrowding	a large and densely populated urban area; may include several independent administrative districts