viewpoint vs vantage

viewpoint and vantage both are nouns.

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

As nouns, vantage is a hypernym of viewpoint; that is, vantage is a word with a broader meaning than viewpoint:

viewpoint: a place from which something can be viewed
vantage: place or situation affording some advantage (especially a comprehensive view or commanding perspective)

viewpoint (noun)	vantage (noun)
a mental position from which things are viewed	the quality of having a superior or more favorable position
a place from which something can be viewed	place or situation affording some advantage (especially a comprehensive view or commanding perspective)