We here discuss a new model of gamma-ray bursts (GRBs) based on differ
entially rotating strange stars. Strange stars in this model and diffe
rentially rotating neutron stars in the Kluzniak-Ruderman model can pr
oduce extremely relativistic, variable fireballs required by GRBs and
then become millisecond pulsars. The effect of such pulsars on expansi
on of the postburst fireballs through magnetic dipole radiation is stu
died. We show that these two models can explain naturally not only var
ious features of GRBs but also light curves of afterglows. [S0031-9007
(98)07701-1].