Ostrava vs urban center

Ostrava and urban center both are nouns.

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

Ostrava (noun)	urban center (noun)
an industrial city in northwestern Czech Republic in the Moravian lowlands; located in the coal mining area of Silesia	a large and densely populated urban area; may include several independent administrative districts