looker-on vs spectator

looker-on and spectator both are nouns.

Word	Noun	Adjective	Verb	Adverb
looker-on	Yes	No	No	No
spectator	Yes	No	No	No

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

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

Other hypernyms of looker-on include looker, viewer, watcher, witness.

looker-on (noun)	spectator (noun)
someone who looks on	a woman's pump with medium heel; usually in contrasting colors for toe and heel
	a close observer; someone who looks at something (such as an exhibition of some kind)