The paper presents the results of calculation and analysis of the trajectories and emission spectra of ultrarelativistic electrons and positrons with an energy of 375 MeV channeling in straight and periodically bent diamond crystals with a length of 20 and 40 μm. The numerical simulation of planar channeling of particles along the crystallographic plane (110) is carried out using the MBN Explorer package. The parameters of the particle beams and the orientation of the crystals are chosen close to the experimental conditions at the MAMI accelerator (Mainz, Germany). The comparison between the results obtained for electrons and positrons is performed.