Osaka vs city

Osaka and city both are nouns.

Word	Noun	Adjective	Verb	Adverb
Osaka	Yes	No	No	No
city	Yes	No	No	No

Osaka (noun)	city (noun)
port city on southern Honshu on Osaka Bay; a commercial and industrial center of Japan	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts
	an incorporated administrative district established by state charter