Average speed is the ratio of the total distance to total time. The average velocity is the rate at which position changes. That is average velocity is the ratio of total displacement to the total time.
The speed is a scalar quantity and the velocity is a vector quantity.
The distance is the total length of the path of the object, whereas the displacement is the straight or the minimum distance between the initial and the final position of the object.
Therefore when an object completes its motion, the distance traveled by the object can be larger than the displacement.
Thus, an object can have a high average speed but a small average velocity.