urban center vs Hiroshima

urban center and Hiroshima both are nouns.

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

urban center (noun)	Hiroshima (noun)
a large and densely populated urban area; may include several independent administrative districts	a port city on the southwestern coast of Honshu in Japan; on August 6, 1945 Hiroshima was almost completely destroyed by the first atomic bomb dropped on a populated area