impropriety vs demeanour

impropriety and demeanour both are nouns.

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

As nouns, demeanour is a hypernym of impropriety; that is, demeanour is a word with a broader meaning than impropriety:

impropriety: an improper demeanor
demeanour: (behavioral attributes) the way a person behaves toward other people

Other hypernyms of impropriety include behavior, behaviour, conduct, demeanor, deportment.

impropriety (noun)	demeanour (noun)
an act of undue intimacy	(behavioral attributes) the way a person behaves toward other people
an indecent or improper act
an improper demeanor
the condition of being improper