organ stop vs sourdine

organ stop and sourdine both are nouns.

Word	Noun	Adjective	Verb	Adverb
organ stop	Yes	No	No	No
sourdine	Yes	No	No	No

As nouns, sourdine is a hyponym of organ stop; that is, sourdine is a word with a more specific, narrower meaning than organ stop:

Other hyponyms of organ stop include diapason, diapason stop, dulciana, flue stop, reed stop, voix celeste, vox angelica.

organ stop (noun)	sourdine (noun)
a graduated set of organ pipes of like tone quality	an organ stop resulting in a soft muted sound
	a mute for a violin