Nonlinear optical phenomena at nanoscale have recently become important in the research field of silicon photonics. Among these, stimulated Raman scattering is one of the most interesting, due to its significant implications from both fundamental and applicative point of view. In this work, comparison among experimental investigations of stimulated Raman scattering in amorphous silicon nanoparticles and in silicon micro- and nano-crystals, at the wavelengths of interest for telecommunications, are reported. The physical insight related to different nanostructures are discussed and their Raman gain and bandwidth are compared to an ideal material.