block up vs block off

block up and block off both are verbs.

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

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

Other synonyms of block up include bar, barricade, block, blockade, stop.

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

Other hyponyms of block up include close off, shut off, close.

block up (verb)	block off (verb)
render unsuitable for passage	obstruct access to
	render unsuitable for passage
	block off the passage through