A comparative analysis of a fast atom beam and ion beam effect on a metal target in the binary collision model is performed. Irradiation by fast atoms has been shown to more closely correspond to neutron radiation in a nuclear reactor, in terms of the primary knocked-on atom spectrum and the efficiency and mechanism of the radiation defect formation. It was found that upon irradiation by fast carbon atoms with an energy of 0.2-0.3 MeV, the average number of radiation defects in the displacement cascade of one atom is four to five times higher than the calculated values using the SRIM program for ions with the same energy. It is shown that during penetration in the target, the probability of ionization of atoms with energies less than 0.4 MeV is negligible.