parlour grand piano vs baby grand piano

parlour grand piano and baby grand piano both are nouns.

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

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

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

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