bait vs stool pigeon

bait and stool pigeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
bait	Yes	No	Yes	No
stool pigeon	Yes	No	No	No

As nouns, stool pigeon is a hyponym of bait; that is, stool pigeon is a word with a more specific, narrower meaning than bait:

bait: something used to lure fish or other animals into danger so they can be trapped or killed
stool pigeon: a dummy pigeon used to decoy others

Other hyponyms of bait include chum, fish lure, fisherman's lure, ground bait.

bait (noun)	stool pigeon (noun)
something used to lure fish or other animals into danger so they can be trapped or killed	a dummy pigeon used to decoy others
anything that serves as an enticement	someone acting as an informer or decoy for the police

bait (verb)	stool pigeon (verb)
harass with persistent criticism or carping
attack with dogs or set dogs upon
lure, entice, or entrap with bait