Completely different kites.

I've flown an '07 Rebel 12, but i own an '08 Alliance 12.
I'd describe the Rebel as more of a smooth-hybrid to fly, whilst the Alliance is a bit heavier and industrial. Bar pressure is higher on the Alliance but not uncomfortably so.
From other people that have flown my Alliance it's a bit of a love or hate kite; and i love it. Definitely try and get a demo before you buy one.

I don't think JB can answer as he has gone underground for a while. It seems he's not the Messiah, he's a very naughty boy

But back on topic as Koma alluded to these 2 kites are very different.
The Rebel will have the bigger wind range and makes more power for it's size.
The Alliance will be more suited to riders who like the C kite feel in a hybrid kite.

Jason

I own & use quite frequently an 8m & 12m alliance, awesome kite
The 12m is a bit heavy, but work very well & quick

Have flown the north rebels also, nice kite but the niash feels better to fly

Andrew