Grain Flavor Profiles
For brewing and distilling, barley is the most common and modified grain. Heavy flavors to use as the base for most whiskies.
Malted 2 row barley is considered a base malt. It can comprise 100% of a grain bill for a simple basic single malt whiskey. It is high in starches.
Lower sugar levels but higher conversion enzymes make this popular for distillers.
Maize or Corn
For pure sugar content and cost corn can't be beat. Adds sweetness and lightens up flavor.
Wheat adds a smooth gentle flavor to a whiskey. Added as minor part of a grain bill it makes a partner to other grains. Generally not used a majority of a grain bill.
Rye is a very strongly flavored grain with spicey and grass like notes. While it can be used as 100% of a grain bill, it normally is an accent to bourbon.