Difference between relaxation time and collision time?

For the answer to the question above, let us first start with relaxation time. it is the absence of an external electric field, the free electrons in a metallic substance will move in random directions so that the resultant velocity of free electrons in any direction is equal to zero. While the Collision time it is the mean time required for the direction of motion of an individual type particle to deviate through approximately as a consequence of collisions with particles of type.