Portsmouth vs city

Portsmouth and city both are nouns.

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

Portsmouth (noun)	city (noun)
a port town in southeastern New Hampshire on the Atlantic Ocean	people living in a large densely populated municipality
a port city in southern England on the English Channel; Britain's major naval base	a large and densely populated urban area; may include several independent administrative districts
a port city in southeastern Virginia on the Elizabeth River opposite Norfolk; naval base; shipyards	an incorporated administrative district established by state charter