To understand the difference between Speed and Velocity, let’s look at the following example:
A driver reached a junction and is deciding if he should travel westward (left side of diagram) or eastward (right side of diagram). Let’s define the westward direction to be negative and the eastward direction to be positive.
If the driver decides to move to westward and after 1 hour, he has travelled 60 kilometres, the speed of the car is 60km/hr. However, its velocity would be -60km/hr.
Had the driver moved eastward from the junction and travelled 60 kilometres after an hour, the speed of the car would be 60km/hr and its velocity would be positive 60km/hr: