What is the difference between LKAS and RDM

I was wondering if anyone could shed some light on the difference between these two systems on the 2016 RLX. Both appear to be used to keep your car in the lane when driving. I know my Advance with the LKAS and ACC will actual drive the car and keep it in the lane or make curves, etc for about 10 sec before telling me to put my hands on the steering wheel.