eye vs peeper

eye and peeper both are nouns.

Word	Noun	Adjective	Verb	Adverb
eye	Yes	No	Yes	No
peeper	Yes	No	No	No

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

eye (noun)	peeper (noun)
a small hole or loop (as in a needle)	an animal that makes short high-pitched sounds
the organ of sight	an informal term referring to the eye
good discernment (either visually or as if visually)	a viewer who enjoys seeing the sex acts or sex organs of others
attention to what is seen
an area that is approximately central within some larger region

eye (verb)	peeper (verb)
look at