outnumber vs add up

outnumber and add up both are verbs.

Word	Noun	Adjective	Verb	Adverb
outnumber	No	No	Yes	No
add up	No	No	Yes	No

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

Other hypernyms of outnumber include amount, come, number, total.

outnumber (verb)	add up (verb)
be larger in number	determine the sum of
	be reasonable or logical or comprehensible
	to measure up to in kind or quality
	add up in number or quantity