The differential sensing approach uses fingerprint patterning to distinguish uncharacterized biological samples. Inspired by natural sensory systems, an array of cross-reactive sensors generates unique response fingerprint depending on the samples. Until today, this array system has been developed using various materials, including the library of surface-charged nanoparticles and chemosensors. Many differential array systems have demonstrated accurate identification of bacterial species, viral subtypes, and cancer cells, as well as distinguishing disease states in blood or urine. This capability is particularly important for distinguishing between normal and abnormal states when specific marker molecules have not yet been identified, providing a powerful diagnostic tool. In this concept, we summarized representative outcomes of differential sensing applications for biological sample discrimination.