Bourbon (distilled from corn) and Rye are whiskies distilled in the U.S. We in the U.S. refer to whisky distilled in Scotland (mostly from malted barley) as "Scotch." If you walk into a pub or bar in Britain and ask for a "whisky & soda," you will be served Scotch & soda. In Ireland, it will be made with Irish whiskey (the Irish spell it with an 'e').
Just as all champagne is sparkling wine, but not all sparkling wine is champagne, all scotch is whisky, but not all whisky is scotch.
