RL Sir,
Forgive my presumptuousness in answering your question, as I know that you know a great deal about Bourbon and American Whiskeys. I myself once asked this question, and many others regarding the subtle differences. I attended college in Nashville TN in close proximity to the origin of both Bourbon and Tennessee Whiskey and spent many a night in the comfortable grip of one, the other, or both. (I now prefer JD to JB, and Bookers is my favorite) As it was explained to me by a class mate and relative of the family from Lynchburg... Tennessee Whiskey is simply called Tennessee Whiskey. The term American Whiskey is thrown around lightly encompasses American Rye, Bourbon and Tennessee Whiskeys. Really each should be simply called what they are. I have enclosed some links with interesting history and explanantions for those that care to venture. When it comes down to it, a good Tennesse Whiskey or Bourbon, both have the same wonderful effects.
http://www.straightbourbon.com/articles/ccname.html http://www.mindspring.com/~mccarthys/whiskey/corn.htm http://ellenjaye.com/lg-academy2003.htm