draw back vs back up

draw back and back up both are verbs.

Word	Noun	Adjective	Verb	Adverb
draw back	No	No	Yes	No
back up	No	No	Yes	No

As verbs, back up is a hyponym of draw back; that is, back up is a word with a more specific, narrower meaning than draw back:

Other hyponyms of draw back include fall back, retreat, retrograde, back down, back off.

draw back (verb)	back up (verb)
use a surgical instrument to hold open (the edges of a wound or an organ)	establish as valid or genuine
pull back or move away or backward	become or cause to become obstructed
	make a copy of (a computer file) especially for storage in another place as a security copy
	move backwards from a certain position
	give moral or psychological support, aid, or courage to