improperness vs demeanour

improperness and demeanour both are nouns.

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

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

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

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

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