stock split vs step-up

stock split and step-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
stock split	Yes	No	No	No
step-up	Yes	No	No	No

As nouns, step-up is a hypernym of stock split; that is, step-up is a word with a broader meaning than stock split:

stock split: an increase in the number of outstanding shares of a corporation without changing the shareholders' equity
step-up: the act of increasing something

Other hypernyms of stock split include increase.

stock split (noun)	step-up (noun)
an increase in the number of outstanding shares of a corporation without changing the shareholders' equity	the act of increasing something