toilet vs potty chair

toilet and potty chair both are nouns.

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

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

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

toilet (noun)	potty chair (noun)
the act of dressing and preparing yourself	toilet consisting of a small seat used by young children
a room or building equipped with one or more toilets
a plumbing fixture for defecation and urination
misfortune resulting in lost effort or money