For FEM based programs mesh influences results especially over point supports so you should have identical / very similar meshing in both programs. If you make your mesh denser in these locations the values of bending moment will increase too. This is the reason for reduction over the support option in Robot which allow to reduce these unwanted peeks of bending for reinforcement calculations. In addition mind that the values depends on the direction of the projection of the results. The default for cuts in Robot is along the cut - I don't know how this is done in Orion but you have to make sure that you compare the same results. For maps in Robot you set the direction as automatic which is along the local X. Check also if you compare the same results (Mxx or Myy) - along the cut or perpendicular to the cut. Last but not least check the values of loads (sum of reactions) for the load case / combination you compare results for. They should be the same in both programs.