The results of numerical modeling of horizontal pneumatic conveying of polyethylene pellets are presented. Two different techniques have been applied to track the particle trajectories: discrete element method (DEM) and discrete particle model (DPM). Particle-particle and particle-wall collisions in DEM are treated using a soft-spheres approach. In contrast, a hard-spheres modeling of particle-wall interactions is realized in DPM. The unsteady numerical calculations simulated the behavior of particles in a wide range of flow regimes, beginning from dilute and ending with dense particle flows. The advantages of DPM are fast computations and reduced requirements of computer resources owing to larger time step and smaller amount of stored information than DEM. However, the results of calculations show that DPM is more appropriate for modeling of dilute particle flow (particle volume fraction less than 10%), whereas the DEM approach can be successfully utilized for simulation of various flow regimes between low and large particle concentrations.