confirm vs back up

confirm and back up both are verbs.

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

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

Other hyponyms of confirm include back, vouch, verify, demonstrate, establish, prove, shew, show, document, validate.

confirm (verb)	back up (verb)
make more firm	establish as valid or genuine
establish or strengthen as with new evidence or facts	become or cause to become obstructed
strengthen or make more firm	make a copy of (a computer file) especially for storage in another place as a security copy
administer the rite of confirmation to	move backwards from a certain position
support a person for a position	give moral or psychological support, aid, or courage to