vigil vs overwatch

vigil and overwatch both are nouns.

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

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

vigil: a purposeful surveillance to guard or observe
overwatch: surveillence by a unit within a video game which would cause the unit to make an action in response to an enemy unit's action

Other hyponyms of vigil include continuous receiver watch, listening watch, spying.

vigil (noun)	overwatch (noun)
a purposeful surveillance to guard or observe	surveillence by a unit within a video game which would cause the unit to make an action in response to an enemy unit's action
the rite of staying awake for devotional purposes (especially on the eve of a religious festival)
a period of sleeplessness