manners vs demeanour

manners and demeanour both are nouns.

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

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

manners: social deportment
demeanour: (behavioral attributes) the way a person behaves toward other people

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

manners (noun)	demeanour (noun)
social deportment	(behavioral attributes) the way a person behaves toward other people