As someone on the Warlord HP stated, there will be no difference between the Royalist and Parliamentarian boxes besides cover art and included flags.
Anyway, it's clever marketing: For picky guys like me, the boxes obviously give me only some options that need to be complemented by other (likely metal) miniatures: Marching and fighting models don't go very well together in one unit, and there are way too few pikemen (especially armoured ones) in one box. No nagging, just compliments to the sales staff at Warlord's.

At least, I'm happy to see those musket rests again.
