There are many different kinds of whiskey, ("whisky" to Scotsmen) all distilled end products of fermented grain mash, usually barley, corn, wheat, or rye. Techniques for brewing and distilling, local soils, and ancillary ingredients determine types.
"Malt" refers to barley, anything else is "grain" whisk(e)y. Scotch whiskies have a strong peat aroma due to the soil, and Irish whiskies are similar to Scotch but smother due to more distillation and less (or no) peat.
American whiskies usually contain corn, there are countless variations. "Tennessee whiskey" for example, is like bourbon but filtered through charcoal, and Canadian whiskies usually have more rye. In the US, if it is called by an ingredient (eg "rye" whiskey) then it must be over 50% that grain in the mash.