What is the difference between velocity and average velocity?

Explanation

Average velocity : If an object undergoes a displacement `Delta vec(r)` in a time `Delta t` , then average velocity is :
`vec(v)_("avg") = (Delta vec(r))/(Delta t)`
It is a vector quantity, direction is in the direction of `Delta vec(r)`
Velocity : Limiting value of the average velocity as `Delta t to 0` called velocity .
`vec(v) = lim_(Delta t to 0)(Delta vec(r))/(Delta t) = (d vec(r))/(dt)`