battery charger vs device

battery charger and device both are nouns.

Word	Noun	Adjective	Verb	Adverb
battery charger	Yes	No	No	No
device	Yes	No	No	No

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

battery charger: a device that can hold a rechargeable battery by means of an electrical cable
device: an instrumentality invented for a particular purpose

battery charger (noun)	device (noun)
a device that can hold a rechargeable battery by means of an electrical cable	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