For coherent targets, Huynen then Cameron proposed a set of characteristic parameters deduced from monostatic full polarimetric scattering matrices. Among these parameters, the two Authors have considered two parameters connected to the same physical properties: orientation and symmetry degree. As the Huynen definition seems to be more intuitive, we will try to compare these parameters by simulations with the aim to test the real connection of the Huynen parameters to physical properties. This study will show significant differences. However, it is shown that the Huynen parameters correctly represent the orientation and the symmetry degree for nearly symmetric targets. In some cases (real eigenvalues in particular), the two orientation angles can be equal to an ambiguity of 45°, even for asymmetric targets.