improperness vs impropriety

improperness and impropriety both are nouns.

Word	Noun	Adjective	Verb	Adverb
improperness	Yes	No	No	No
impropriety	Yes	No	No	No

As nouns, improperness and impropriety are synonyms defined as:

improperness (noun)	impropriety (noun)
an improper demeanor	an act of undue intimacy
	an indecent or improper act
	an improper demeanor
	the condition of being improper