bystander vs spectator

bystander and spectator both are nouns.

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

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

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

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

bystander (noun)	spectator (noun)
a nonparticipant spectator	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)