peephole vs spyhole

peephole and spyhole both are nouns.

Word	Noun	Adjective	Verb	Adverb
peephole	Yes	No	No	No
spyhole	Yes	No	No	No

As nouns, peephole and spyhole are synonyms defined as:

peephole and spyhole: a hole (in a door or an oven etc) through which you can peep

Other synonyms of peephole include eyehole.

peephole (noun)	spyhole (noun)
a hole (in a door or an oven etc) through which you can peep	a hole (in a door or an oven etc) through which you can peep