crapper vs potty chair

crapper and potty chair both are nouns.

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

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

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

crapper (noun)	potty chair (noun)
a plumbing fixture for defecation and urination	toilet consisting of a small seat used by young children