back up vs choke up

back up and choke up both are verbs.

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

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

Other hyponyms of back up include gum up, block, lug, stuff, silt, silt up.

back up (verb)	choke up (verb)
establish as valid or genuine	obstruct
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