Angular velocity is the rate of change of the angular position with respect to time. It is generally measured in radians per unit time (e.g. seconds) or sometimes in revolutions per minute (rpm). Angular velocity is basically the measure of how fast something goes around a circular path independent of how large the circle is (i.e. independent of radius).
ω = 2pif
where ω = angular velocity and f = angular frequency
Linear velocity is defined as the rate of change of displacement between an object and a fixed point. It is the measure of how fast an object goes from point A to point B.