piano keyboard vs keyboard

piano keyboard and keyboard both are nouns.

Word	Noun	Adjective	Verb	Adverb
piano keyboard	Yes	No	No	No
keyboard	Yes	No	No	No

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

piano keyboard: a bank of keys on a musical instrument
keyboard: device consisting of a set of keys on a piano or organ or typewriter or typesetting machine or computer or the like

piano keyboard (noun)	keyboard (noun)
a bank of keys on a musical instrument	holder consisting of an arrangement of hooks on which keys or locks can be hung
	device consisting of a set of keys on a piano or organ or typewriter or typesetting machine or computer or the like