Working autofocus, no compass errors, all around obstacle detection, 4S power, Occusync 2.0 performs much better around interference, 1080p live view on device, landing lights, 3 position flight mode switch allows ATTI mode withing giving up Sport mode, 3 minute camera swaps between Pro and Zoom... and probably some other things.
I fly Spark, Air, M1P, M1PP,
M2P,
M2Z, P3P,
P4P, P4A, P4PO, I1,
I2 plus FPV. The reliability and solid flight performance on the M2 is exceptional and the batteries are the best performing of any of the DJI family, with a couple of mine over 200 cycles now and still putting out ~20km flights. APAS and sensors, while not perfect, are a huge improvement over the
M1. I can use Active Track Profile, APAS on and ride my bike without worrying about tree branches or other obstacles. The M2 flies around them and doesn't lose the shot.