drift ice vs ice

drift ice and ice both are nouns.

Word	Noun	Adjective	Verb	Adverb
drift ice	Yes	No	No	No
ice	Yes	No	Yes	No

As nouns, ice is a hypernym of drift ice; that is, ice is a word with a broader meaning than drift ice:

drift ice (noun)	ice (noun)
masses of ice floating in the open sea	a rink with a floor of ice for ice hockey or ice skating
	an amphetamine derivative (trade name Methedrine) used in the form of a crystalline hydrochloride; used as a stimulant to the nervous system and as an appetite suppressant
	a frozen dessert with fruit flavoring (especially one containing no milk)
	a flavored sugar topping used to coat and decorate cakes
	the frozen part of a body of water
	diamonds
	water frozen in the solid state