  In bulk Sr$_{2}$RuO$_{4}$, the strong sensitivity of the superconducting
transition temperature $T_{\text{c}}$ to nonmagnetic impurities provides robust
evidence for a superconducting order parameter that changes sign around the
Fermi surface. In superconducting epitaxial thin-film Sr$_{2}$RuO$_{4}$, the
relationship between $T_{\text{c}}$ and the residual resistivity $\rho_0$,
which in bulk samples is taken to be a proxy for the low-temperature elastic
scattering rate, is far less clear. Using high-energy electron irradiation to
controllably introduce point disorder into bulk single-crystal and thin-film
Sr$_{2}$RuO$_{4}$, we show that $T_{\text{c}}$ is suppressed in both systems at
nearly identical rates. This suggests that part of $\rho_0$ in films comes from
defects that do not contribute to superconducting pairbreaking, and establishes
a quantitative link between the superconductivity of bulk and thin-film
samples.
