I'm wondering the same, and for me the issue is whether it is worthwhile jumping into the new bar system.
From what I can gather, the kites are the same, but the 2014 bridles are different to fit the new 2014 bar/lines. No pulleys in 2014, so the feeling is apparently more direct and kites are a bit quicker. Also the 2014 bar makes it easier to self land the kites.
I've flown both in demos, but not back to back, and FWIW as a wave novice I didn't notice a heap of difference.
Big enough difference in the 2013 to 2014 Drifters to make it worth getting the 2014 models. New bar, lower V (aids the quicker turning), newer bridal (one pulley). New material in the canopy.
The 11m turns so quick. A guy was out at my local spot on a marginal day in about 13 knots on a Blade 17m Fat Lady, I took the 11m Drifter out and had a blast.
Try both if you can and see for yourself.