A Tennessee whiskey is for the most part very similar to bourbon, but there are some differences. It must be made from a mash with at least 51 percent single grain, usually corn. The distillate must not exceed 160 proof, it must then be aged in oak barrels for at least two years, and the final product must not be diluted to less than 80 proof (40% ABV).
The biggest difference between bourbon and Tennessee whiskey is that the latter must be slowly filtered through sugar-maple charcoal, something that give it a sweet characteristic.
Well known Tennessee whiskeys are Jack Daniel's and George Dickel (see related ingredients).