What is differences between magnitudes and velocity?

Magnitude is simply a numerical quantity or value.

Generally in physics, it refers to the quantity or distance. With respect to movement, we can correlate the magnitude with the size and speed of the object while travelling.

Let us understand it with an example – we have the temperature of three cities 24℃, 12℃, and 5℃. We add only the magnitudes and the unit remains the same. Here,  24, 12, 5 is the magnitude, and ℃ is the unit. 

A car is running at a velocity of 60km/h. Here, 60 is the magnitude and km/h is the unit.

Velocity is defined as the rate of change of displacement with respect to time. It is nothing but the speed at which an object moves in a particular direction. It is a vector quantity. It needs both magnitude and direction to represent it. 

The unit of velocity is meter/second (m/s).

Mathematically, velocity is given as:

$V=\frac{D}{T}$

where, V = velocity, D = displacement, and t = time