  We consider the Froggatt-Nielsen (FN) mechanism reproducing the observed mass
hierarchies and mixing angles for quarks and leptons. The large $\nu_\mu $-$
\nu_\tau$ mixing suggested from recent Superkamiokande experiments on the
atmospheric neutrinos implies lopsided FN U(1) charges for the lepton doublets.
There are two possible charge assignments to generate the large $\nu_\mu$-$
\nu_\tau$ mixing. We point out that the two models with different charge
assignments have distinct low-energy predictions and hence they are
distinguishable in future neutrino experiments on such as CP violation and
$2\beta 0\nu$ decay.
