Mobile vs urban center

Mobile and urban center both are nouns.

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

Mobile (noun)	urban center (noun)
a port in southwestern Alabama on Mobile Bay	a large and densely populated urban area; may include several independent administrative districts
a river in southwestern Alabama; flows into Mobile Bay