back up vs pull away

back up and pull away both are verbs.

Word	Noun	Adjective	Verb	Adverb
back up	No	No	Yes	No
pull away	No	No	Yes	No

As verbs, pull away is a hypernym of back up; that is, pull away is a word with a broader meaning than back up:

Other hypernyms of back up include draw back, move back, pull back, recede, retire, retreat, withdraw.

back up (verb)	pull away (verb)
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