straighten vs pull up

straighten and pull up both are verbs.

Word	Noun	Adjective	Verb	Adverb
straighten	No	No	Yes	No
pull up	No	No	Yes	No

As verbs, pull up is a hyponym of straighten; that is, pull up is a word with a more specific, narrower meaning than straighten:

Other hyponyms of straighten include rear, rise up, draw up, straighten up.

straighten (verb)	pull up (verb)
put (things or places) in order	remove, usually with some force or effort; also used in an abstract sense
make straight or straighter	cause (a vehicle) to stop
make straight	come to a halt after driving somewhere
straighten by unrolling	straighten oneself
straighten up or out; make straight
get up from a sitting or slouching position