the pits vs region

the pits and region both are nouns.

Word	Noun	Adjective	Verb	Adverb
the pits	Yes	No	No	No
region	Yes	No	No	No

As nouns, region is a hypernym of the pits; that is, region is a word with a broader meaning than the pits:

Other hypernyms of the pits include part.

the pits (noun)	region (noun)
any place of pain and turmoil	a part of an animal that has a special function or is supplied by a given artery or nerve
	a knowledge domain that you are interested in or are communicating about
	the extended spatial location of something
	a large indefinite location on the surface of the Earth
	the approximate amount of something (usually used prepositionally as in `in the region of')