Experimental data are presented on the multiplicities of the charged secondaries of the various types in the interactions of 6Li and 7Li projectile isotopes with the target nuclei in nuclear emulsion at 4.5 A GeV/c and 3.7 A GeV/c, respectively. A systematic comparison using the corresponding values of 4He-Em interactions is made. The results are discussed in the frameworks of the cascade evaporation, "wounded" nucleons, and generalized Andersson-Otterlund-Stenlund (AOS) models.