All bourbon is made from a mash bill that's at least 51% corn, but the remaining grains — the secondary and tertiary grains — have an outsized influence on the final flavor. The two dominant grain combinations are rye-recipe (also called high-rye) and wheated, and understanding the difference is one of the most useful pieces of knowledge a bourbon drinker can acquire.
Rye-recipe bourbon uses rye as its secondary grain, typically making up 10–35% of the mash bill. Rye brings spice: black pepper, cinnamon, dried herbs, and a certain grippy, assertive character that some describe as "dry." It tends to produce bourbons with a longer, more complex finish. The majority of Kentucky bourbons — Four Roses, Wild Turkey, Jim Beam, and most of the Heaven Hill lineup — are rye-recipe. If you like your bourbon with backbone and spice, this is your lane.
Wheated bourbon substitutes wheat for rye, creating a softer, rounder, and generally sweeter profile. Wheat doesn't fight the corn the way rye does; it steps back and lets the oak and vanilla flavors come forward. The result is often described as "approachable" or "gentle," which has made wheated bourbons enormously popular. Maker's Mark is the most recognizable example, but the style finds its greatest expression in the Pappy Van Winkle line and its siblings — W.L. Weller and Old Fitzgerald — which use the same wheated mash bill from Buffalo Trace Distillery. The high demand for wheated bourbons has made many of these bottles difficult to find, but Buffalo Trace itself and Maker's Mark remain widely available at reasonable prices.