Gehenna vs nether region

Gehenna and nether region both are nouns.

Word	Noun	Adjective	Verb	Adverb
Gehenna	Yes	No	No	No
nether region	Yes	No	No	No

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

Gehenna: a place where the wicked are punished after death
nether region: (Christianity) the abode of Satan and the forces of evil; where sinners suffer eternal punishment

Other hypernyms of Gehenna include Hell, infernal region, Inferno, perdition, pit.

Gehenna (noun)	nether region (noun)
a place where the wicked are punished after death	(Christianity) the abode of Satan and the forces of evil; where sinners suffer eternal punishment