bystander vs looker

bystander and looker both are nouns.

Word	Noun	Adjective	Verb	Adverb
bystander	Yes	No	No	No
looker	Yes	No	No	No

As nouns, looker is a hypernym of bystander; that is, looker is a word with a broader meaning than bystander:

bystander: a nonparticipant spectator
looker: a close observer; someone who looks at something (such as an exhibition of some kind)

Other hypernyms of bystander include spectator, viewer, watcher, witness.

bystander (noun)	looker (noun)
a nonparticipant spectator	a very attractive or seductive looking woman
	a close observer; someone who looks at something (such as an exhibition of some kind)