charger vs battery charger

charger and battery charger both are nouns.

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

As nouns, charger and battery charger are synonyms defined as:

charger and battery charger: a device that can hold a rechargeable battery by means of an electrical cable

charger (noun)	battery charger (noun)
formerly a strong swift horse ridden into battle	a device that can hold a rechargeable battery by means of an electrical cable
a device that can hold a rechargeable battery by means of an electrical cable