watcher vs ogler

watcher and ogler both are nouns.

Word	Noun	Adjective	Verb	Adverb
watcher	Yes	No	No	No
ogler	Yes	No	No	No

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

watcher: a close observer; someone who looks at something (such as an exhibition of some kind)
ogler: a viewer who gives a flirtatious or lewd look at another person

watcher (noun)	ogler (noun)
a guard who keeps watch	a viewer who gives a flirtatious or lewd look at another person
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