keep back vs withhold

keep back and withhold both are verbs.

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

As verbs, keep back and withhold are synonyms defined as:

keep back (verb)	withhold (verb)
prevent the action or expression of	hold back; refuse to hand over or share
hold back; refuse to hand over or share	retain and refrain from disbursing; of payments
secure and keep for possible future use or application