stool vs potty chair

stool and potty chair both are nouns.

Word	Noun	Adjective	Verb	Adverb
stool	Yes	No	Yes	No
potty chair	Yes	No	No	No

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

Other hyponyms of stool include flushless toilet, flush toilet, lavatory, potty seat.

stool (noun)	potty chair (noun)
a simple seat without a back or arms	toilet consisting of a small seat used by young children
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

stool (verb)	potty chair (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