cash register vs money box

cash register and money box both are nouns.

Word	Noun	Adjective	Verb	Adverb
cash register	Yes	No	No	No
money box	Yes	No	No	No

As nouns, money box is a hypernym of cash register; that is, money box is a word with a broader meaning than cash register:

cash register: a cashbox with an adding machine to register transactions; used in shops to add up the bill
money box: a strongbox for holding cash

Other hypernyms of cash register include cashbox, till.

cash register (noun)	money box (noun)
a cashbox with an adding machine to register transactions; used in shops to add up the bill	a strongbox for holding cash
	a container (usually with a slot in the top) for keeping money at home