teething ring vs device

teething ring and device both are nouns.

Word	Noun	Adjective	Verb	Adverb
teething ring	Yes	No	No	No
device	Yes	No	No	No

As nouns, device is a hypernym of teething ring; that is, device is a word with a broader meaning than teething ring:

teething ring (noun)	device (noun)
device used for an infant to suck or bite on	any clever maneuver
	an instrumentality invented for a particular purpose
	an emblematic design (especially in heraldry)
	any ornamental pattern or design (as in embroidery)
	something in an artistic work designed to achieve a particular effect