This work compares the 4H- and 6H-SiC Rutherford Back-Scattering channeling spectra and angular dips for low index axes and planes: the spectra and the dip shoulders show features that depend on the polytype, while the dip amplitudes do not. In the light of the theories of the ion scattering within crystals such behaviour shows that the two polytypes have different channeling stopping powers but similar interaction potentials, and, as well known, different long range atomic site simmetry. Some dip shoulders are so peculiar that they can be taken as the polytype finger printing in the RES spectrometry.