Channeling and x-ray diffraction measurements on Kr- and He-irradiated V3Si single crystals and films reveal different damage levels for fluences in cases where the superconducting transition temperature T chas been reduced by the same amount. This indicates that only special defect structures are responsible for the T c-reduction mechanism. In the fluence region where T cis decreasing, T ccorrelates with residual resistivity ϱo, independent of the kind of irradiation. However, at particle fluences where T csaturation occurs, different saturation values of ϱo are observed. The exponential decrease and the saturation of T cwith fluence are explained by a similar behavior of g9o versus fluence in the damage production and saturation processes. The increase of the lattice parameter is not uniquely dependent on the decrease of T c, but also on the amount of damage present.