sex up vs alter

sex up and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
sex up	No	No	Yes	No
alter	No	No	Yes	No

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

Other hypernyms of sex up include change, modify.

sex up (verb)	alter (verb)
give erotic character to or make more interesting	remove the ovaries of
	become different in some particular way, without permanently losing one's or its former characteristics or essence
	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to