hunch over vs change posture

hunch over and change posture both are verbs.

Word	Noun	Adjective	Verb	Adverb
hunch over	No	No	Yes	No
change posture	No	No	Yes	No

As verbs, change posture is a hypernym of hunch over; that is, change posture is a word with a broader meaning than hunch over:

hunch over: round one's back by bending forward and drawing the shoulders forward
change posture: undergo a change in bodily posture

hunch over (verb)	change posture (verb)
round one's back by bending forward and drawing the shoulders forward	undergo a change in bodily posture