Dear student,

The magnitude of the velocity at any instant of time (t) is known as instantaneous speed or simply speed at that instant of time.

Quantitatively :- speed = distance/time

Speed is a scalar quantity and it can never be negative.

The time rate of change of position or displacement at any instant of time (t) is known as instantaneous velocity or simply velocity at that instant of time.

Quantitatively :- velocity = displacement/ time

Velocity is a vector quantity and it can be positive, negative and zero.