back up vs promote

back up and promote both are verbs.

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

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

back up (verb)	promote (verb)
establish as valid or genuine	make publicity for; try to sell (a product)
become or cause to become obstructed	change a pawn for a better piece by advancing it to the eighth row, or change a checker piece for a more valuable piece by moving it to the row closest to your opponent
make a copy of (a computer file) especially for storage in another place as a security copy	be changed for a superior chess or checker piece
move backwards from a certain position	give a promotion to or assign to a higher position
give moral or psychological support, aid, or courage to	contribute to the progress or growth of