subdivide vs split up

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

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

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

Other hypernyms of subdivide include carve up, dissever, divide, separate, split.

subdivide (noun)	split up (noun)
	an increase in the number of outstanding shares of a corporation without changing the shareholders' equity

subdivide (verb)	split up (verb)
divide into smaller and smaller pieces	become separated into pieces or fragments
form into subdivisions	get a divorce; formally terminate a marriage
	discontinue an association or relation; go different ways
	separate into parts or portions