back up vs occlude

back up and occlude both are verbs.

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

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

Other hypernyms of back up include block, close up, impede, jam, obstruct, obturate.

back up (verb)	occlude (verb)
establish as valid or genuine	block passage through
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