electric refrigerator vs icebox

electric refrigerator and icebox both are nouns.

Word	Noun	Adjective	Verb	Adverb
electric refrigerator	Yes	No	No	No
icebox	Yes	No	No	No

As nouns, icebox is a hypernym of electric refrigerator; that is, icebox is a word with a broader meaning than electric refrigerator:

electric refrigerator: a refrigerator in which the coolant is pumped around by an electric motor
icebox: white goods in which food can be stored at low temperatures

Other hypernyms of electric refrigerator include refrigerator.

electric refrigerator (noun)	icebox (noun)
a refrigerator in which the coolant is pumped around by an electric motor	white goods in which food can be stored at low temperatures