A Rietveld refinement uses as input a powder diffraction pattern. Such a diffraction pattern is obtain from a polycrystalline sample, i.e. in most cases a powdered sample. Software to refine a powder diffraction pattern via the Rietvald algorithm are for example Fullprof, Maud, Jana, Topaz, GSAS-II etc etc.

Diffraction data from a single crystal on the other hand are obtain by diffraction of a (small) single individual crystal, where the diffraction off all the planes hkl is collected. Essentially all such data are the integrated intensities of individual Bragg "reflections". Software would be Shelx, Olex, etc.

There are a few program that can do both single crystal refinement and Rietveld refinment, (Jana, GSAS-II... ) yet always the input data dictate the type of refinement to do.

Sometimes it is possible to integrate the individual Bragg reflections in a powder diffraction pattern to obtain a (partial) list of integrated Bragg reflections.