footstool vs stool

footstool and stool both are nouns.

Word	Noun	Adjective	Verb	Adverb
footstool	Yes	No	No	No
stool	Yes	No	Yes	No

As nouns, stool is a hypernym of footstool; that is, stool is a word with a broader meaning than footstool:

footstool (noun)	stool (noun)
a low seat or a stool to rest the feet of a seated person	a simple seat without a back or arms
	a plumbing fixture for defecation and urination
	(forestry) the stump of a tree that has been felled or headed for the production of saplings
	solid excretory product evacuated from the bowels

footstool (verb)	stool (verb)
	have a bowel movement
	grow shoots in the form of stools or tillers
	react to a decoy, of wildfowl
	lure with a stool, as of wild fowl