straighten vs modify

straighten and modify both are verbs.

Word	Noun	Adjective	Verb	Adverb
straighten	No	No	Yes	No
modify	No	No	Yes	No

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

Other hypernyms of straighten include alter, change.

straighten (verb)	modify (verb)
put (things or places) in order	make less severe or harsh or extreme
make straight or straighter	add a modifier to a constituent
make straight	cause to change; make different; cause a transformation
straighten by unrolling
straighten up or out; make straight
get up from a sitting or slouching position