The difference between Aluminium foil and Foil

Aluminium foil as a noun (AU, NZ, British):

A very thin, pliable, easily torn sheet of aluminium used for cooking, packaging, cosmetics, and insulation.

Foil as a noun:

A very thin sheet of metal.

Foil as a noun (uncountable):

Thin aluminium/aluminum (or, formerly, tin) used for wrapping food.

Foil as a noun:

A thin layer of metal put between a jewel and its setting to make it seem more brilliant.

Foil as a noun (authorship, figuratively):

In literature, theatre/theater, etc., a character who helps emphasize the traits of the main character and who usually acts as an opponent or antagonist.

Foil as a noun (figuratively):

Anything that acts by contrast to emphasise the characteristics of something.

Foil as a noun (fencing):

A very thin sword with a blunted (or foiled) tip

Foil as a noun:

A thin, transparent plastic material on which marks are made and projected for the purposes of presentation. See transparency.

Foil as a noun (heraldiccharge):

A stylized flower or leaf.

Foil as a noun:

A hydrofoil.

Foil as a noun:

An aerofoil/airfoil.

Foil as a verb:

To prevent (something) from being accomplished.

Foil as a verb:

To prevent (someone) from accomplishing something.

Foil as a verb:

To blunt; to dull; to spoil.

Foil as a verb (obsolete):

To tread underfoot; to trample.

Foil as a noun:

Failure when on the point of attainment; defeat; frustration; miscarriage.

Foil as a noun:

One of the incorrect answers presented in a multiple-choice test.

Foil as a noun (hunting):

The track of an animal.

Foil as a verb (mathematics):

To expand a product of two or more algebraic expressions, typically binomials.

Foil as a verb (obsolete):

To defile; to soil.