Granular flows occur in various contexts including laboratory experiments, industrial processes and natural geophysical flows. In order to investigate their dynamics, different kinds of physically-based models have been developed. These models can be characterized by the length scale at which dynamic processes are described. Discrete models use a microscopic scale to model individually each grain, Navier-Stokes models use a mesoscopic scale to consider elementary volumes of grains, and thin-layer models use a macroscopic scale to model the dynamics of elementary columns of fluids. In each case, the derivation of the associated equations is well known. However, few studies focus on the extent to which these modeling solutions yield mutually coherent results. In this work, we compare the simulations of a granular dam break on a horizontal or inclined plane, for the discrete model COCD, the Navier-Stokes model Basilisk, and the thin-layer model SHALTOP. We show that, although all three models allow reproducing the temporal evolution of the free surface in the horizontal case (except for SHALTOP at the initiation), the modeled flow dynamics are significantly different, and in particular during the stopping phase. The pressures measured at the flow's bottom are in relatively good agreement, but significant variations are obtained with the COCD model due to complex and fast-varying granular lattices. Similar conclusions are drawn using the same rheological parameters to model a dam break on an inclined plane. This comparison exercise is essential for assessing the limits and uncertainties of granular flow modeling.