hold back vs hold on

hold back and hold on both are verbs.

Word	Noun	Adjective	Verb	Adverb
hold back	No	No	Yes	No
hold on	No	No	Yes	No

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

Other hypernyms of hold back include keep.

hold back (verb)	hold on (verb)
prevent the action or expression of	be persistent, refuse to stop
hold back, as of a danger or an enemy; check the expansion or influence of	stop and wait, as if awaiting further instructions or developments
hold back; keep from being perceived by others	hold the phone line open
secure and keep for possible future use or application	hold firmly
wait before acting	retain possession of
refrain from doing