  Despite the structural resemblance of certain cuprate and nickelate parent
compounds there is a striking spread of $T_c$ among such transition metal oxide
superconductors. We adopt a minimal two-orbital $e_g$ model which covers
cuprates and nickelate heterostructures in different parametric limits, and
analyse its superconducting instabilities. The joint consideration of
interactions, doping, Fermiology, and in particular the $e_g$ orbital splitting
allows us to explain the strongly differing pairing propensities in cuprate and
nickelate superconductors.
