buy time vs hold up

buy time and hold up both are verbs.

Word	Noun	Adjective	Verb	Adverb
buy time	No	No	Yes	No
hold up	No	No	Yes	No

As verbs, hold up is a hypernym of buy time; that is, hold up is a word with a broader meaning than buy time:

buy time: act so as to delay an event or action in order to gain an advantage
hold up: cause to be slowed down or delayed

Other hypernyms of buy time include delay, detain.

buy time (verb)	hold up (verb)
act so as to delay an event or action in order to gain an advantage	cause to be slowed down or delayed
	be the physical support of; carry the weight of
	hold up something as an example; hold up one's achievements for admiration
	rob at gunpoint or by means of some other threat
	continue to live and avoid dying
	resist or withstand wear, criticism, etc.
	resist or confront with resistance