* Speed is a scalar quantity: It only describes the magnitude (how fast) of an object's motion, not its direction.

* Magnitude is always positive: The magnitude of any quantity is always a non-negative value.

Example:

Imagine a car traveling at 50 km/h. Its speed is 50 km/h, regardless of whether it's moving east, west, north, or south.

Velocity, however, can be negative. Velocity is a vector quantity, meaning it includes both magnitude and direction. So, a car traveling at 50 km/h east would have a positive velocity, while a car traveling at 50 km/h west would have a negative velocity.