movel can be called with a pose or joint positions (with fk in the later case). As the forward kinematic maps several joint positions to the same pose it can destroy information. Is there a guarantee that moveL(joints) and moveJ(joints) reach the same joint configuration on different paths?
In short: no, there is no such guarantee. If you pass a joint state to
movel() it will perform forwards kinematics and do the same as if you gave it that pose directly. In general, it isn’t possible to plan a linear path in cartesian space to a given joint position. There might not be a valid path.
Theoretically the controller could plan a linear cartesian path and check if the resulting joint position matches the input and throw an error if this is not the case. However, that is not what the UR controller does.