  Let $\{U_n\}_{n \geqslant 0}$ and $\{G_m\}_{m \geqslant 0}$ be two linear
recurrence sequences defined over the integers. We establish an asymptotic
formula for the number of integers $c$ in the range $[-x, x]$ which can be
represented as differences $ U_n - G_m$, when $x$ goes to infinity. In
particular, the density of such integers is $0$.
