Here's my synopsis of the Service Highlights.
DSC is a steering safety system. It's activated in cornering when it determines a sudden change in vehicle attitude is causing sideslip because the car is at or close to an understeer or oversteer condition. It can inform the PCM to lower engine output, and/or have the DSC hydraulic unit apply more/less/maintain fluid pressure to each individual brake caliper piston to suppress the oversteer/understeer condition.
TCS is activated when it sees that the drive wheels are slipping, and can inform the PCM to lower engine output, and/or have the DSC HU apply more/less/maintain fluid pressure to each caliper piston to control the slipping drive wheel.
They work together and in conjunction with the ABS, and Electronic Brake Distrubution control, steering angle and wheel speed sensors to prevent wheel lockup, wheel spin, oversteer, understeer, and maintain steering ability by actuating torque reduction thru fuel cut and ignition timing, as well as turning on and off solenoids, pumps and valves providing individual brake control to maintain traction.
It's saved my butt several times, and makes driving tight canyons a BLAST!!