* Speed is a scalar quantity, meaning it only has magnitude (how fast something is moving).

* Velocity is a vector quantity, meaning it has both magnitude *and* direction.

Example:

Imagine a car driving around a circular track at a constant speed of 60 miles per hour.

* Constant speed: The car is always moving at 60 mph.

* Variable velocity: Even though the speed is constant, the car's *direction* is constantly changing as it goes around the circle. Since velocity includes direction, the velocity is changing.

In short: You can have constant speed with changing velocity if the direction of motion changes.