FACS and flow cytometry are partners in the process of cell analysis. FACS stands for fluorescence-activated cell sorting. It is a cell sorting process in which a sample cell mixture is sorted according to their fluorescence and light scattering characteristics. Flow cytometry focuses on analyzing a mixed population of cells based on their unique characteristics such as size, volume, and cell surface molecules. This allows for the examination of individual cells within the population.  Although both FACS and flow cytometry differentiate cells according to their optical properties and can be used interchangeably, there are a few distinct differences in the methodology between the two processes. Also, both have different procedural outcomes.