Question

What is velocity .. how it is different from speed?

Answer 1

The short answer is that velocity is the speed with a direction, while speed does not have a direction. Speed is a scalar quantity -- it is the magnitude of the velocity. Speedis measured in units of distance divided by time, e.g. miles per hour, feet per second, meters per second, etc....

Answer 2

The rate of displacement is known as velocity
It is a vector quantity whereas speed is scalar quantity