Whiskey vs Whisky
The terms whiskey and whisky come about primarily from geographic differences.In the United States and Ireland, grain alcohols are referred to as whiskey, while in Canada and Scotland, they call it whisky.
Scotch vs Whiskey
The first difference is that scotch whisky is spelled without the "e" in whiskey. All Scotch is whisky (or whiskey), not all whisky is Scotch.