  We discuss how transitions in the space of heterotic K3*T^2 compactifications
are mapped by duality into transitions in the space of Type II
compactifications on Calabi-Yau manifolds. We observe that perturbative
symmetry restoration, as well as non-perturbative processes such as changes in
the number of tensor multiplets, have at least in many cases a simple
description in terms of the reflexive polyhedra of the Calabi-Yau manifolds.
Our results suggest that to many, perhaps all, four-dimensional N=2 heterotic
vacua there are corresponding type II vacua.
