What's the difference between Rye and Bourbon? Is it the grains? (Rye vs corn). According to chemist Thomas Collins at the University of California at Davis the answer is no.  The answer is in the wood of the barrels used to age the whiskey. Go here:
To complicate matters further Rye and Bourbons made at the same distillery had flavor profiles which resemble each other more than to other Ryes and Bourbons.