Displacement describes how far out of place an object is when comparing its initial and final positions. Displacement is a vector quantity which is always conscious of the direction of motion and any changes in that direction. Distance is a scalar quantity which is ignorant of the direction of travel and any changes in direction.
Suppose that a person walks 12 meters, east and then 4 meters, west. The distance traveled is 16 meters. The fact that there was a direction change is irrelevant to any measurement of the distance. The displacement of the object is 8 meters, east. The fact that there is a direction change must be considered when measuring the displacement. Displacement must account for the fact that the 4 meter segment of the motion was in the opposite direction as the 12 meter segment. For the displacement measurement, the 4 meters is considered as a negative (a directional adjective) and added onto the +12 meters.
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