From various videos, that cover free stuff and patch info, we can see quite a few changes to the old WE units. We still won't be shown DLC stuff
1) Orion can shoot while moving.
2) Glade Riders with spears are here. 550 gold, same as Ellyrian Reavers (Reavers seem straight up better, but that is probably more the case of Reavers being too cheap)
3) Buffed Treekin
-5MD, +28 WS, vanguard
4) All tree units got vanguard, don't know if it include Lords like Ancient Treemen and Durthu, but Treeman unit has vanguard
5) Hawk Riders got vanguard and 360 firing
6) Glade Captain on a Great Stag AKA Stagtain
These are very, very, very strong buffs, without even accessing DLC stuff.