town vs borough

town and borough both are nouns.

Word	Noun	Adjective	Verb	Adverb
town	Yes	No	No	No
borough	Yes	No	No	No

As nouns, borough is a hyponym of town; that is, borough is a word with a more specific, narrower meaning than town:

town: the people living in a municipality smaller than a city
borough: an English town that forms the constituency of a member of parliament

town (noun)	borough (noun)
the people living in a municipality smaller than a city	one of the administrative divisions of a large city
an urban area with a fixed boundary that is smaller than a city	an English town that forms the constituency of a member of parliament
an administrative division of a county