Answer with Explanation:
velocity and speed are the same for a 100-m sprint but not a 400-m sprint because velocity is Displacement/Time i.e since in 100-m sprint race, the athlete run from point A to B on a straight line (distance traveled in a specific direction - Displacement), but in 400-m sprint race, the athlete run from point A back to point A (coming back to the origin), the athlete didn't just travel in one direction.
Therefore their velocity and speed can't be the same since they don't have equal displacement.