posture vs viewpoint

posture and viewpoint both are nouns.

Word	Noun	Adjective	Verb	Adverb
posture	Yes	No	Yes	No
viewpoint	Yes	No	No	No

As nouns, viewpoint is a hyponym of posture; that is, viewpoint is a word with a more specific, narrower meaning than posture:

Other hyponyms of posture include hard line, point of view, stand, standpoint.

posture (noun)	viewpoint (noun)
the arrangement of the body and its limbs	a mental position from which things are viewed
characteristic way of bearing one's body	a place from which something can be viewed
capability in terms of personnel and materiel that affect the capacity to fight a war
a rationalized mental attitude

posture (verb)	viewpoint (verb)
assume a posture as for artistic purposes
behave affectedly or unnaturally in order to impress others