Real wood veneer, non-parrallel cabinet sides (reduction in standing waves), semi-seperate tweeter housing (better imaging, less cabinet difraction), on the 700 series.
Better driver components, better crossover parts and design, better tweeter design (surround), on the new 600 series.
The B&W guys seem to prefer the CM series as well, and have intonated that the 700 series are going away.
It would seem a comparative audition will be in order.
I am a SALESMAN, if I am not telling you to automatically ASSUME the 700 series (more expensive) is better, then YOU SHOULD TAKE NOTICE, and if the B&W guys are shrugging their shoulders, take notice too.