vigil vs viewing

vigil and viewing both are nouns.

Word	Noun	Adjective	Verb	Adverb
vigil	Yes	No	No	No
viewing	Yes	No	No	No

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

vigil: the rite of staying awake for devotional purposes (especially on the eve of a religious festival)
viewing: a vigil held over a corpse the night before burial

Other hyponyms of vigil include wake, agrypnia.

vigil (noun)	viewing (noun)
a purposeful surveillance to guard or observe	a vigil held over a corpse the night before burial
the rite of staying awake for devotional purposes (especially on the eve of a religious festival)	the display of a motion picture
a period of sleeplessness