parlor grand piano vs parlour grand

parlor grand piano and parlour grand both are nouns.

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

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

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

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