behavior vs manner

behavior and manner both are nouns.

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

As nouns, manner is a hyponym of behavior; that is, manner is a word with a more specific, narrower meaning than behavior:

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

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