The structural and dynamical properties of C60 chains inserted inside Single Walled carbon Nanotubes (SWNT) have been investigated by x-ray and neutron diffraction, and inelastic neutron scattering (INS). The measurements have been performed on a large mass of a very high quality carbon peapods sample. We showed that powder diffraction could hardly give definitive response on the way the C60s are bonded inside SWNT. However, the comparison of the neutron-derived generalized density of states (GDOS) of the inserted C60 peas with the GDOS of the same objects derived from lattice dynamics calculations led to unambiguous results. The observation of excitations in the 8–15 meV range is a clear evidence for the presence strong bonds between C60s in the sample. In the same time, the observation of a very weak quasi-elastic signal may be related to rotational motions of C60 monomers inside the SWNT. These results suggest that peapods are made of a mixed phase of C60 monomers and C60 n-mers.