hold on vs uphold

hold on and uphold both are verbs.

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

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

Other hypernyms of hold on include bear on, carry on, continue, preserve.

hold on (verb)	uphold (verb)
be persistent, refuse to stop	stand up for; stick up for; of causes, principles, or ideals
stop and wait, as if awaiting further instructions or developments	support against an opponent
hold the phone line open	keep or maintain in unaltered condition; cause to remain or last
hold firmly
retain possession of