Whisky or whiskey?

In Ireland and America the normal spelling of whiskey is with an "e". In all other whisky producing countries, including Scotland and Japan, it is whisky without an "e".

There is no obvious reason why and it’s not a big issue. Indeed, in America some whiskies spell it without the "e" and over time the spelling has swung from one to the other. 

And what is whisk(e)y?

While the rules about what can be called Scotch are clear and rigid, there is not a globally accepted definition of whisky. It is a general rule that whisky is a distilled spirit made from a fermented mash of grain cereals and aged, to some degree, in oak casks. Barley, corn (maize), rye and wheat are the most commonly used cereals.

And while Scotch and Irish whisky stipulate a minimum ageing period of three years, for Bourbon it is two, while others have no legal minimum.