parlour grand piano vs baby grand

parlour grand piano and baby grand both are nouns.

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

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

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

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