foil vs aluminum foil

foil and aluminum foil both are nouns.

Word	Noun	Adjective	Verb	Adverb
foil	Yes	No	Yes	No
aluminum foil	Yes	No	No	No

As nouns, aluminum foil is a hyponym of foil; that is, aluminum foil is a word with a more specific, narrower meaning than foil:

Other hyponyms of foil include aluminium foil, tin foil, chaff, gold foil, tin foil, tinfoil.

foil (noun)	aluminum foil (noun)
a light slender flexible sword tipped by a button	foil made of aluminum
a piece of thin and flexible sheet metal
picture consisting of a positive photograph or drawing on a transparent base; viewed with a projector
a device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through
anything that serves by contrast to call attention to another thing's good qualities

foil (verb)	aluminum foil (verb)
cover or back with foil
hinder or prevent (the efforts, plans, or desires) of
enhance by contrast