ah, looks like this might be a duplicate... I'll put it in here as I'll never find it again otherwise! :)

Breakthrough 1: Total improvement of performance
2M880N adopts high performance DSP motor control chip, current control will be more precise if combined with space vector current control technique. Low frequency vibration of stepper motor will be much improved.
2M880N optimize motor power drive circuit, so even the drive current is raised 2A higher than 2M860, the temperature of drive stays almost the same, meanwhile the working noise is lower.
Subdivision accuracy is 3 times higher than 2M860, the maximum pulse input frequency is 400 KHz.

Breakthrough 2: 5 functions are newly added, easy to use
The five newly added functions such as alarm output, single/double pulse, motor parameter adaptation, phase memory and trial operation will bring wholly new use's experience.
The motor adaptation function could detect the motor it drives and allocate the most appropriate parameter to make sure the motor run in the best condition. Open collector alarm output, the output port could adapt with the most of PLCs. Host computer could monitor the drive working condition at any time which improves controllability of the whole equipment. Phase memory could assure stepper motor won't vibrate after power-off restart. Clients don't have to worry about unplanned outages anymore.

Features:
Motor parameter adaptation
Drive trial operation
Phase memory
Single/double control pulse input
Automatic semi-current
Optocoupler isolation ERR fault signal output, the maximum current is 20 mA
16 mirco-step. Maxium is 256
Overvoltage, undervoltage, overheat, overcurrent alarm


All of this is well over my head so I'm greatful for the discussion about it.

I'm non the wiser, but I am much better informed! :-)