The pulley arrangements of Figs. (a) and (b) are identical. The mass of the rope is negligible

The pulley arrangements of Figs. (a) and (b) are identical. The mass of the rope is negligible. In (a) the mass m is lifted up by attaching a mass 2m to the other end of the rope. In (b), m is lifted up by pulling the other end of the rope with a constant downward force `F=2mg`. The acceleration of m is the same in both cases