Distance is a scalar quantity that refers to "how much ground an object has covered" during its motion.

Displacement is a vector quantity that refers to "how far out of place an object is"; it is the object's overall change in position.

Suppose you walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. Even though you have walked a total distance of 12 meters, your displacement is 0 meters.