defroster vs warmer

defroster and warmer both are nouns.

Word	Noun	Adjective	Verb	Adverb
defroster	Yes	No	No	No
warmer	Yes	No	No	No

As nouns, warmer is a hypernym of defroster; that is, warmer is a word with a broader meaning than defroster:

defroster: heater that removes ice or frost (as from a windshield or a refrigerator or the wings of an airplane)
warmer: device that heats water or supplies warmth to a room

Other hypernyms of defroster include heater.

defroster (noun)	warmer (noun)
heater that removes ice or frost (as from a windshield or a refrigerator or the wings of an airplane)	device that heats water or supplies warmth to a room