You'll really need to check with your local HD to nitpick the differences. These regulations vary not only from state to state, but often from county to county, and in some cases, even city to city.
Where I live, the legal stuff is pretty liberal and practically anybody can set up shop and cook on a roadside corner. But go two miles over into the next county, or cross the state line, and even a fully licensed food truck is strictly prohibited, and there's no certifications or licenses you can get to make it happen.
So your best bet is to start with the Tennessee health code, and then ask your local health department what the restrictions are based on where you want to sell, because it could be vastly different from what others are experiencing.