close up vs block

close up is not a noun while block is a noun.

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

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

Other synonyms of close up include impede, jam, obstruct, obturate, occlude.

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

close up (noun)	block (noun)
	the act of obstructing or deflecting someone's movements
	a solid piece of something (usually having flat rectangular sides)
	an obstruction in a pipe or tube
	a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope
	a metal casting containing the cylinders and cooling ducts of an engine
	a platform from which an auctioneer sells
	housing in a large building that is divided into separate units
	an inability to remember or think of something you normally can do; often caused by emotional tension
	a number or quantity of related things dealt with as a unit
	a rectangular area in a city surrounded by streets and usually containing several buildings
	(computer science) a sector or group of sectors that function as the smallest data unit permitted
	a three-dimensional shape with six square or rectangular sides

close up (verb)	block (verb)
refuse to talk or stop talking; fall silent	shape into a block or blocks
block passage through	shape by using a block
unite or bring into contact or bring together the edges of	prohibit the conversion or use of (assets)
cease to operate or cause to cease operating	be unable to remember
	interfere with or prevent the reception of signals
	impede the movement of (an opponent or a ball)
	render unsuitable for passage
	obstruct
	stamp or emboss a title or design on a book with a block
	support, secure, or raise with a block
	block passage through
	shut out from view or get in the way so as to hide from sight
	interrupt the normal function of by means of anesthesia
	hinder or prevent the progress or accomplishment of
	stop from happening or developing
	run on a block system

close up (adverb)	block (adverb)
very close