Klavier vs keyboard instrument

Klavier and keyboard instrument both are nouns.

Word	Noun	Adjective	Verb	Adverb
Klavier	Yes	No	No	No
keyboard instrument	Yes	No	No	No

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

Klavier: a stringed instrument that has a keyboard
keyboard instrument: a musical instrument that is played by means of a keyboard

Other hypernyms of Klavier include stringed instrument.

Klavier (noun)	keyboard instrument (noun)
a stringed instrument that has a keyboard	a musical instrument that is played by means of a keyboard