parlour grand vs grand piano

parlour grand and grand piano both are nouns.

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

As nouns, grand piano is a hypernym of parlour grand; that is, grand piano is a word with a broader meaning than parlour grand:

parlour grand: a small grand piano
grand piano: a piano with the strings on a horizontal harp-shaped frame; usually supported by three legs

Other hypernyms of parlour grand include grand.

parlour grand (noun)	grand piano (noun)
a small grand piano	a piano with the strings on a horizontal harp-shaped frame; usually supported by three legs