potty seat vs potty chair

potty seat and potty chair both are nouns.

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

As nouns, potty seat and potty chair are synonyms defined as:

potty seat and potty chair: toilet consisting of a small seat used by young children

potty seat (noun)	potty chair (noun)
toilet consisting of a small seat used by young children	toilet consisting of a small seat used by young children