piousness vs devoutness

piousness and devoutness both are nouns.

Word	Noun	Adjective	Verb	Adverb
piousness	Yes	No	No	No
devoutness	Yes	No	No	No

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

Other hyponyms of piousness include religiousness, dutifulness, godliness.

piousness (noun)	devoutness (noun)
righteousness by virtue of being pious	piety by virtue of being devout