  Relativistic mean field calculations suggest that the charge and matter
deformations significantly differ in some of the unstable neutron and proton
rich nuclei. We discuss the effects of the difference on the fusion reactions
induced by them at energies near and below the Coulomb barrier by taking the
$^{19,25,37}$Na + $^{208}$Pb reactions as examples. We also discuss whether one
can probe the difference by the so called fusion barrier distribution analysis.
