fragment vs split up

fragment and split up both are nouns.

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

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

Other hypernyms of fragment include break, come apart, fall apart, separate.

fragment (noun)	split up (noun)
a broken piece of a brittle artifact	an increase in the number of outstanding shares of a corporation without changing the shareholders' equity
an incomplete piece
a piece broken off or cut off of something else

fragment (verb)	split up (verb)
break or cause to break into pieces	become separated into pieces or fragments
	get a divorce; formally terminate a marriage
	discontinue an association or relation; go different ways
	separate into parts or portions