For example, the House Atreides campaign will closely follow the storyline of the Dune novel. As the campaign progresses, Paul will have to perform the actions necessary to become the Kwisatz Haderach, and unite the mighty Fremen with the remnants of the Atreides forces to overcome their Harkonnen oppressors, and inflict a fierce vengeance upon the turncoat Emperor. Meanwhile in the Harkonnen campaign, as a potential Kwisatz Haderach of similar bloodlines, Feyd must endeavour to seize this power for himself. Approximately 40 Units per side, a third of which are unique to each of the four Houses. That's a total of almost 100 unique, varied and complex Units to play with.
Units gain new abilities and prowess with experience.
Your most battle-hardy warriors will be carried over to future missions. Increased mission continuity. Campaign missions are no longer independent entities. Secondary objectives can be accomplished in earlier missions to turn future conflicts to your advantage. Excess finances are carried over from mission to mission.