manner vs behavior

manner and behavior both are nouns.

Word	Noun	Adjective	Verb	Adverb
manner	Yes	No	No	No
behavior	Yes	No	No	No

As nouns, behavior is a hypernym of manner; that is, behavior is a word with a broader meaning than manner:

manner: a way of acting or behaving
behavior: (behavioral attributes) the way a person behaves toward other people

Other hypernyms of manner include behaviour, conduct, demeanor, demeanour, deportment.

manner (noun)	behavior (noun)
a way of acting or behaving	manner of acting or controlling yourself
how something is done or how it happens	(psychology) the aggregate of the responses or reactions or movements made by an organism in any situation
a kind	(behavioral attributes) the way a person behaves toward other people
	the action or reaction of something (as a machine or substance) under specified circumstances