What is the difference between lane departure warning and lane keeping assist?

Lane Departure Warning (LDW) alerts the driver when the vehicle unintentionally drifts from its lane, using visual, audible, or haptic (vibration) warnings. Lane Keeping Assist (LKA) actively applies steering torque to help keep the vehicle within lane markings. Lane Centering Assist (LCA) continuously steers to keep the vehicle centered in the lane. These systems use cameras to detect lane markings. LDW is informational only, while LKA/LCA provide control assistance. LKA typically activates only when the driver is not signaling and may disengage if the driver does not hold the steering wheel. Combined with ACC, LKA/LCA forms L2 highway pilot systems.