straighten out vs alter

straighten out and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
straighten out	No	No	Yes	No
alter	No	No	Yes	No

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

Other hypernyms of straighten out include change, modify.

straighten out (verb)	alter (verb)
put (things or places) in order	remove the ovaries of
settle or put right	become different in some particular way, without permanently losing one's or its former characteristics or essence
change for the better	cause to change; make different; cause a transformation
make free from confusion or ambiguity; make clear	insert words into texts, often falsifying it thereby
make straight	make an alteration to
extricate from entanglement