break up vs crack

break up is not a noun while crack is a noun.

Word	Noun	Adjective	Verb	Adverb
break up	No	No	Yes	No
crack	Yes	Yes	Yes	No

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

Other hyponyms of break up include digest, dissociate.

As verbs, break up and crack are synonyms defined as:

Other synonyms of break up include collapse, crack up, crock up.

break up (noun)	crack (noun)
	the act of cracking something
	a usually brief attempt
	a narrow opening
	a purified and potent form of cocaine that is smoked rather than snorted; highly addictive
	a blemish resulting from a break without complete separation of the parts
	witty remark
	a sudden sharp noise
	a long narrow cleft
	a long narrow depression in a surface
	a chance to do something

break up (adjective)	crack (adjective)
	of the highest quality

break up (verb)	crack (verb)
laugh unrestrainedly	break suddenly and abruptly, as under tension
break or cause to break into pieces	become fractured; break or crack on the surface only
come to an end	break partially but keep its integrity
separate (substances) into constituent elements or parts	cause to become cracked
cause to go into a solution	reduce (petroleum) to a simpler compound by cracking
cause to separate	break into simpler molecules by means of heat
close at the end of a session	pass through (a barrier)
bring the association of to an end or cause to break up	tell spontaneously
make a break in	hit forcefully; deal a hard blow, making a cracking noise
set or keep apart	suffer a nervous breakdown
break violently or noisily; smash	make a sharp sound
attack with or as if with a pickaxe of ice or rocky ground, for example	make a very sharp explosive sound
release ice	gain unauthorized access computers with malicious intentions
destroy the completeness of a set of related items
take apart into its constituent pieces
suffer a nervous breakdown
disband
to cause to separate and go in different directions
discontinue an association or relation; go different ways