  We investigate the signal $\gamma\gamma$ + missing energy in a high-energy
linear $e^+e^-$ collider, with a view to differentiating between gauge-mediated
supersymmetry breaking and the conventional supersymmetric models. Prima facie,
there is considerable chance of confusion between the two scenarios if the
assumption of gaugino mass unification is relaxed. We show that the use of
polarized electron beams enables one to distinguish between the two schemes in
most cases. There are some regions in the parameter space where this idea does
not work, and we suggest some additional methods of distinction. We also
perform an analysis of some signals in the gauge-mediated model, coming from
the pair production of the second-lightest neutralino.
