soberness vs somberness

soberness and somberness both are nouns.

Word	Noun	Adjective	Verb	Adverb
soberness	Yes	No	No	No
somberness	Yes	No	No	No

As nouns, soberness and somberness are synonyms defined as:

Other synonyms of soberness include graveness, gravity, sobriety, sombreness.

soberness (noun)	somberness (noun)
a manner that is serious and solemn	a manner that is serious and solemn
the state of being sober and not intoxicated by alcohol	a feeling of melancholy apprehension
	a state of partial or total darkness