The properties of x-ray diffraction are compared for two principally different scattering mechanisms: potential and resonant. The first mechanism is well represented by elastic scattering from atomic electrons (Rayleigh scattering), while the second one is offered by recoilless resonant scattering from nuclei (M\"ossbauer scattering). Diffraction in Bragg geometry from a semi-infinite crystal is considered. Mainly, the spatial aspects of scattering are discussed like angular dependencies, distributions of electric and magnetic fields inside the crystal and, especially, the role of asymmetry in the diffraction geometry. The results of the model calculations are presented for a complex reflection coefficient, for total wave fields and their interaction with atoms, for path lengths in transmission of radiation through the crystal, and for an interplay between absorption and reflection of radiation by the atomic ensemble.