Near-field impact assessment of atmospheric releases requires simulations of flow and dispersion that take into account the complexity of the natural and/or anthropogenic environment. These simulations must therefore be carried out on the basis of 3D models. However, 3D models can be very different: for example, diagnostic or CFD flow models and Lagrangian or Eulerian dispersion models. In this article, we consider the dispersion of releases from an industrial facility on a terrain with marked topography and varied land use. Simulations are carried out using both PMSS and Code_SATURNE, the results of which are compared on sensors placed in the environment of the site as well as in terms of plume shapes. We analyze which meteorological situations (atmospheric stability and wind speed) are conducive to obtaining rather similar dispersion results and explain in which situations the results are dissimilar. Thus, our article contributes to the more informed use of 3D models in near-field atmospheric dispersion studies.