The boxed version of the Imperial Edition will contain the game itself as well as a wall chart that will show the real history behind France's most famous general Napoleon Bonaparte. Both the boxed version of the Imperial Edition and the downloadable one (via Steam) will also have a special unlock code that will add 10 exclusive units under the Heroes of the Napoleonic Wars bundle.
But that's not all. The boxed copy of the Imperial Edition as well as the boxed standard retail edition will get access to another Steam code that will download another batch of five exclusive units under the Elite Regiment bundle. So if you want access to all of the exclusive units you have to get the boxed Imperial Edition of the game. Pricing and availability for the special edition has yet to be announced in the US.
Gallery: Napoleon: Total War