Displacement and distance are two different physical quantities. Displacement is a vector with magnitude and direction, and distance is a scalar, that is, only magnitude has no direction.
In one-way linear motion, the distance is the length of the linear trajectory; In curved motion, the distance is the length of the curve trajectory.
When an object returns to its original place after a period of movement, the distance is not zero and the displacement is equal to zero.
In the extended data, there is no direct relationship between velocity direction and displacement direction. Only in linear motion without return (that is, moving in one direction), the direction of speed and the direction of displacement must be the same. In addition, the direction of velocity and displacement can be the same or different.
For example, in the vertical throwing movement, when the object rises, the speed direction (upward) is the same as the displacement direction (upward), while in the falling process, the speed direction (downward) is opposite to the displacement direction (upward) before falling back to the throwing point. If you can continue to fall after passing the throwing point, the speed direction (downward) after that is the same as the displacement direction (downward). Therefore, it is necessary to judge the specific situation.
In curvilinear motion, the directions of velocity and displacement are mostly different. Because the velocity direction is the tangent direction of the trajectory, the connecting line (displacement) direction with any two points on the trajectory mostly forms a non-zero angle.