Peeping Tom vs watcher

Peeping Tom and watcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
Peeping Tom	Yes	No	No	No
watcher	Yes	No	No	No

As nouns, watcher is a hypernym of Peeping Tom; that is, watcher is a word with a broader meaning than Peeping Tom:

Peeping Tom: a viewer who enjoys seeing the sex acts or sex organs of others
watcher: a close observer; someone who looks at something (such as an exhibition of some kind)

Other hypernyms of Peeping Tom include looker, spectator, viewer, witness.

Peeping Tom (noun)	watcher (noun)
a viewer who enjoys seeing the sex acts or sex organs of others	a guard who keeps watch
	a close observer; someone who looks at something (such as an exhibition of some kind)
	a person who keeps a devotional vigil by a sick bed or by a dead body