There is a difference between the unit of work done and the torque acting on the body. The unit of work is Joules ($J$ or $Nm$), whereas that of torque is ($Nm$). Comparing dimension wise, they both have the same; but they are not the same physical quantity. Torque is the rotational analogue of force . While the work done on a body is the dot product of the translation force and the position vector.