  The inclusive spectra of radiative and semi-leptonic B-meson decays near the
endpoint is computed taking into account renormalons in the Sudakov exponent
(Dressed Gluon Exponentiation). In this framework we demonstrate the
factorization of decay spectra into hard, jet and soft functions and discuss
the universality of the latter two. Going beyond perturbation theory the soft
function, which we identify as the longitudinal momentum distribution in an
on-shell b quark, is replaced by the b-quark distribution in the B meson. The
two differ by power corrections. We show how the resummation of
running-coupling effects can be used to perform consistent separation to power
accuracy between perturbative and non-perturbative contributions. In
particular, we prove that the leading infrared renormalon ambiguity in the
Sudakov exponent cancels against the one associated with the definition of the
pole mass. This cancellation allows us to identify the non-perturbative
parameter that controls the shift of the perturbative spectrum in the
heavy-quark limit as the mass difference between the meson and the quark.
