keep back vs confine

keep back and confine both are verbs.

Word	Noun	Adjective	Verb	Adverb
keep back	No	No	Yes	No
confine	No	No	Yes	No

As verbs, confine is a hyponym of keep back; that is, confine is a word with a more specific, narrower meaning than keep back:

keep back (verb)	confine (verb)
prevent the action or expression of	place limits on (extent or amount or access)
hold back; refuse to hand over or share	to close within bounds, or otherwise limit or deprive of free movement
secure and keep for possible future use or application	prevent from leaving or from being removed
	deprive of freedom; take into confinement
	close in