back off vs back up

back off and back up both are verbs.

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

As verbs, back off and back up are synonyms defined as:

Other synonyms of back off include back down.

back off (verb)	back up (verb)
move backwards from a certain position	establish as valid or genuine
remove oneself from an obligation	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