  We investigate the nonperturbative relation between lightcone (LC) and
standard equal-time (ET) quantization in the context of $\lambda \phi^4$ theory
in $d=2$. We discuss the perturbative matching between bare parameters and the
failure of its naive nonperturbative extension. We argue that they are
nevertheless the same theory nonperturbatively, and that furthermore the
nonperturbative map between bare parameters can be extracted from ET
perturbation theory via Borel resummation of the mass gap. We test this map by
using it to compare physical quantities computed using numerical Hamiltonian
truncation methods in ET and LC.
