What differs velocity from speed ?
Velocity is the state of motion of an object.
Velocity is the change in the displacement vector of a moving object with time.
Since displacement is a vector, velocity is also a vector, it has both intensity and direction.
It is always in the same direction as the displacement vector.
It can have a plus or a minus sign.
It is independent of the trajectory followed by the mover.
Speed is the distance an object travels per unit time during its motion.
Since the road taken is scalar, the speed is also scalar, it does not contain direction information.
It can only have positive values, not negative values.
It depends on the length of the orbit.