courtesy of @BigGreen
TRAction Control system . This is refering to TRAC. automatically helps prevent spinning of the rear wheels (2wd models) or 4 wheels (by adding brakes) when the vehicle is started or accelerated on slippery road surfaces.
Doesn't require push button activation. Works on it's own and is activated when the ignition is turned on. all FJ's have this whether 2 or 4wd model. On automatics, I am assuming this works in 2H or 4H, doesn't matter. If the system detects wheel spin, it adds brakes to increase traction.

A-TRAC is Active Traction Control system automatically helps prevent the spinning of 4 wheels when the vehicle is started or accelerated on slippery road surfaces. (basically same as TRAC, but only works in 4 Lo). To activated, hit the ATRAC switch, shift into Nuetral, and shift the 4x4 lever (short knob) into 4 LO. When in 4Lo, it detects wheel slippage and adds brakes accordingly to give added traction. Again, you must be in 4Lo and hit the "ATRAC" switch.



VSC (vehicle stability control) system : integrates the control of the systems such as ABS, TRACtion control, engine control, etc to prevent the vehicle from skidding when cornering on a slippery road surface or operating steering wheel abruptly.
VSC is activated when the vehicle reachs 9mph or 15km/h.
*VSC automatically turns off (VSC off light on dash comes on) when 4H/HL or 4Lo/LL is activated (AT/MT) or when the Rear Diff is locked.