High-resolution x-ray diffraction was used to characterize and compare the exchange process at the interfaces of mixed anion heterostructures. Superlattices (SLs) formed by the Sb-2 exposure of As-stabilized GaAs surfaces and the As-4 exposure of Sb-stabilized GaSb surfaces were grown by molecular beam epitaxy and characterized.. Interface composition profiles have been determined using full dynamical simulations of the SL structures that exhibited anion exchange. Comparisons between As-for-Sb exchange on GaSb and Sb-for-As exchange on GaAs are presented in order to better understand the chemical and physical processes that lead to anion exchange.