straighten out vs clear up

straighten out and clear up both are verbs.

Word	Noun	Adjective	Verb	Adverb
straighten out	No	No	Yes	No
clear up	No	No	Yes	No

As verbs, straighten out and clear up are synonyms defined as:

straighten out and clear up: make free from confusion or ambiguity; make clear

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

Other hypernyms of straighten out include clarify, elucidate.

straighten out (verb)	clear up (verb)
put (things or places) in order	free (the throat) by making a rasping sound
settle or put right	finish a task completely
change for the better	make free from confusion or ambiguity; make clear
make free from confusion or ambiguity; make clear	make clear and (more) comprehensible
make straight	become clear
extricate from entanglement