peep sight vs gun-sight

peep sight and gun-sight both are nouns.

Word	Noun	Adjective	Verb	Adverb
peep sight	Yes	No	No	No
gun-sight	Yes	No	No	No

As nouns, gun-sight is a hypernym of peep sight; that is, gun-sight is a word with a broader meaning than peep sight:

peep sight: rear gunsight having an adjustable eyepiece with a small aperture through which the front sight and the target are aligned
gun-sight: a sight used for aiming a gun

Other hypernyms of peep sight include gunsight.

peep sight (noun)	gun-sight (noun)
rear gunsight having an adjustable eyepiece with a small aperture through which the front sight and the target are aligned	a sight used for aiming a gun