baby grand piano vs parlor grand

baby grand piano and parlor grand both are nouns.

Word	Noun	Adjective	Verb	Adverb
baby grand piano	Yes	No	No	No
parlor grand	Yes	No	No	No

As nouns, baby grand piano and parlor grand are synonyms defined as:

Other synonyms of baby grand piano include baby grand, parlor grand piano, parlour grand, parlour grand piano.

baby grand piano (noun)	parlor grand (noun)
a small grand piano	a small grand piano