Discriminating large extra dimensions at the ILC with polarized beams

Non-standard scenarios described by effective interactions can manifest themselves indirectly, via corrections to the Standard Model cross sections. It should be desirable to identify at a given confidence level the source of such deviations among the different possible explanations. We here discuss the identification reach on gravity in extra dimensions from the four-fermion compositeness-inspired contact interactions and viceversa, using as basic observable the differential cross section of $e^+e^-\to\bar{f}f$ at the ILC, and emphasize the role of beams polarization in enhancing the identification sensitivity.