VPG states:
What's New in 2nd Edition:

Improvements and enhancements to this new edition of Waterloo 20 touch every component, and so it is a complete rebirth. The map has seen a fresh look at the critical terrain that affects these series’ games, and so the addition of several smaller rivers and streams now flow across the landscape. So, too, were some other geographical features more properly placed, and the set up locations of a few units adjusted. The cards have seen many substitutions to improve the game’s narrative, as well as graphics enhancements, to bring them up to the latest series standards. The counters have seen the addition of the French "Grand Battery" artillery Reserve unit, the Prussian Advanced Guard cavalry unit (which begins the game eliminated and awaiting an opportunity to rally, as it was broken earlier slowing down the French approach to Ligny), and a "Good Ground" marker to reflect the strong position Blucher defended at Ligny and Wellington found near Waterloo. The rules include historical and variable weather, and a an 18 June scenario (i.e., the third day) where the pieces begin ready to commence the battles at Wavre and Waterloo. There is even a historical card-draw variant for that scenario, for those desiring a more scripted battle of Waterloo.