I-ABS
Otherwise referred to as Servo Assisted ABS. They seldom go wrong, but when they do, you have no brakes.
The pump consists of 4 separate sections. Front and rear control circuit, and front and rear wheel circuit. Your brake levers control the pump only, via the control circuits. The pump, via the wheel circuits, does the braking on your behalf.
I-ABS2
Straight forward ABS pump that only kicks in when wheel slip is detected. Levers have full control of the braking and braking is not compromised if the pump fails.