XRD pattern is obtained due to periodic arrangement of the atoms in the material. Preparation processes such as sintering, annealing or other such methods affect the ordering of the atoms. Therefore, the XRD pattern depends on such processes.
The degree of crystallinity and chemical order of a sample depends on the manufacturing process: melting, tempering, etc. The X-ray diffraction pattern reveals details of the crystallinity and chemical order of the elements in the resulting sample.
The sharpness of the XRD peaks depends on the crystallinity of the material, by which ever process you make, and tell you about the quality of the material.