impiety vs ungodliness

impiety and ungodliness both are nouns.

Word	Noun	Adjective	Verb	Adverb
impiety	Yes	No	No	No
ungodliness	Yes	No	No	No

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

Other hyponyms of impiety include undutifulness, irreligion, irreligiousness, godlessness.

impiety (noun)	ungodliness (noun)
unrighteousness by virtue of lacking respect for a god	impiety by virtue of not being a godly person