break up vs split

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

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

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

Other hypernyms of break up include part, separate.

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

break up and split: discontinue an association or relation; go different ways

Other synonyms of break up include break, part, separate, split up.

break up (noun)	split (noun)
	division of a group into opposing factions
	the act of rending or ripping or splitting something
	extending the legs at right angles to the trunk (one in front and the other in back)
	an increase in the number of outstanding shares of a corporation without changing the shareholders' equity
	(tenpin bowling) a divided formation of pins left standing after the first bowl
	a dessert of sliced fruit and ice cream covered with whipped cream and cherries and nuts
	an opening made forcibly as by pulling apart
	a lengthwise crack in wood
	a promised or claimed share of loot or money
	a bottle containing half the usual amount

break up (adjective)	split (adjective)
	(especially of wood) cut or ripped longitudinally with the grain
	having been divided; having the unity destroyed

break up (verb)	split (verb)
laugh unrestrainedly	come open suddenly and violently, as if from internal pressure
break or cause to break into pieces	separate or cut with a tool, such as a sharp instrument
come to an end	go one's own way; move apart
separate (substances) into constituent elements or parts	discontinue an association or relation; go different ways
cause to go into a solution	separate into parts or portions
cause to separate
close at the end of a session
bring the association of to an end or cause to break up
make a break in
set or keep apart
break violently or noisily; smash
attack with or as if with a pickaxe of ice or rocky ground, for example
release ice
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