propriety vs demeanour

propriety and demeanour both are nouns.

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

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

propriety: correct or appropriate behavior
demeanour: (behavioral attributes) the way a person behaves toward other people

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

propriety (noun)	demeanour (noun)
correct or appropriate behavior	(behavioral attributes) the way a person behaves toward other people