merge vs alter

merge and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
merge	No	No	Yes	No
alter	No	No	Yes	No

As verbs, alter is a hypernym of merge; that is, alter is a word with a broader meaning than merge:

Other hypernyms of merge include change, modify.

merge (verb)	alter (verb)
become one	remove the ovaries of
mix together different elements	become different in some particular way, without permanently losing one's or its former characteristics or essence
join or combine	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to