there are yeah! there are heroes which have a little more customisation I think, and also spells that are called something like operations, I think the only difference is that the spell points you use in combat and out of combat are different.

oh! I also forgot to mention my absolute favourite change from AoW 3 to Planetfall: the militia. Your cities have inherent defenders that spawn if the place is attacked. They're not enough to survive an actual dedicated attack but they're good for stopping random wandering monsters from taking a city because you didn't wanna dedicate time and resources to making units that are just going to stand on the city for the rest of the game.