The Milky Way bar is a chocolate bar distributed by the Mars confectionery company. The American version of the Milky Way bar is made of chocolate-malt nougat topped with caramel and covered with milk chocolate and is very similar to the Mars bar sold in other countries. The non-US Milky Way bar, on the other hand, is not topped with caramel and is therefore similar to the American 3 Musketeers bar.
The European version of the bar has no caramel topping, and consists of a nougat centre that is considerably lighter than that of the Mars bar. Because of this low density (0,88 g/cm³), it will float in water (and/or in milk) without sinking. This rare attribute was used for an advertising campaign in Germany, France, Russia, Republic of Ireland, Poland, the Netherlands and the United Kingdom.
Originally available within Europe only in chocolate flavor, the center changed to vanilla flavor in 1989, although the chocolate flavor still remains available in Australia. The bar is also available in banana and strawberry flavours. In the UK, Mars introduced the Flyte bar which is identical to the old-style chocolate flavoured Milky Way except in shape. Also available in Europe are Milky Way Crispy Rolls, chocolate covered wafer rolls with a milk-cream filling.
A popular child-oriented derivative of the Milky Way bar known as ‘Milky Way Magic Stars’ is also sold in the UK and consists of small aerated chocolate star shapes. Originally, every star was engraved with a different smiley face, each representing one of the magic star characters portrayed on the packaging. The characters were: Pop Star, Jess Star, Bright Star, Super Star, Happy Star, Sport Star and Baby Star. Recently, however, the characters and their respective engravings have been discontinued, possibly to lower production costs.
Info gleaned from Wikipedia