Just like wine, different bourbons have different bodies (also known as weights, levels of viscosity, or texture). Think of the difference between heavy cream, whole milk, and nonfat milk – they all have a type of slipperiness and fluidity to them. Same with bourbons.
Some bourbons are thick and heavy, sitting on your palate like syrup (think Michters). Other bourbons are very light bodied and almost evaporate on your tongue (think Russell’s Reserve 10 Year Old). Then there are bourbons with the texture of rusty barbed-wire (yes, Old Crow, I’m talking about you). When you do the “Kentucky chew”, note how the bourbon sticks on your tongue, the roof of your mouth, and your teeth and gums.
If you are familiar with wine lingo, you have heard the term “structure” used to describe the interplay of different elements within the wine. Bourbon shares a certain complexity with wine in that the flavor of both are influenced by their ingredients – in this case, the grain that go into the whiskey and bourbon – , their barrels, and their environment. When you describe the heat and the finish of a bourbon, you are in actuality talking about its structure. A nice balanced structure carries enough heat to wake you up, but enough flavor to mellow out the proof.