manners vs demeanor

manners and demeanor both are nouns.

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

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

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

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

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