peeper vs voyeur

peeper and voyeur both are nouns.

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

As nouns, peeper and voyeur are synonyms defined as:

peeper and voyeur: a viewer who enjoys seeing the sex acts or sex organs of others

Other synonyms of peeper include Peeping Tom.

peeper (noun)	voyeur (noun)
an animal that makes short high-pitched sounds	a viewer who enjoys seeing the sex acts or sex organs of others
an informal term referring to the eye
a viewer who enjoys seeing the sex acts or sex organs of others