break up vs sliver

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

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

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

Other hyponyms of break up include atomise, atomize, bray, comminute, crunch, grind, mash, pound, sunder, splinter, rag, crumb, brecciate, crush, grate, grind.

break up (noun)	sliver (noun)
	a thin fragment or slice (especially of wood) that has been shaved from something
	a small thin sharp bit of wood or glass or metal

break up (verb)	sliver (verb)
laugh unrestrainedly	break up into splinters or slivers
break or cause to break into pieces	form into slivers
come to an end	divide into slivers or splinters
separate (substances) into constituent elements or parts
cause to go into a solution
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