Alcohol, malted or not, made from grain which is produced in Scotland is called WHISKY, while it is called WHISKEY if it is produced in USA or Ireland. American whiskey is called Bourbon and is made from grain. Bourbon is at least 51 per cent corn or maize. Scotch whisky is generally double distilled, while Irish whiskey is generally distilled three times. Wheat whisky is the rarest whisky. Rye whiskies are mostly popular within the US. Scotch whisky is whisky that has been distilled and matured in Scotland for at least three hours in oak casks.