city vs Osaka

city and Osaka both are nouns.

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

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