metropolis vs Busan

metropolis and Busan both are nouns.

Word	Noun	Adjective	Verb	Adverb
metropolis	Yes	No	No	No
Busan	Yes	No	No	No

metropolis (noun)	Busan (noun)
people living in a large densely populated municipality	a city in southeastern South Korea on the Korean Strait; the chief port and second largest city
a large and densely populated urban area; may include several independent administrative districts