hold in vs keep back

hold in and keep back both are verbs.

Word	Noun	Adjective	Verb	Adverb
hold in	No	No	Yes	No
keep back	No	No	Yes	No

As verbs, keep back is a hypernym of hold in; that is, keep back is a word with a broader meaning than hold in:

hold in: lessen the intensity of; temper; hold in restraint; hold or keep within limits
keep back: prevent the action or expression of

Other hypernyms of hold in include hold back, keep, restrain.

hold in (verb)	keep back (verb)
hold back; keep from being perceived by others	prevent the action or expression of
lessen the intensity of; temper; hold in restraint; hold or keep within limits	hold back; refuse to hand over or share
close in	secure and keep for possible future use or application