To distinguish crystal-originated particles (COPs) from light point defects (LPDs) in Czochralski-grown silicon (Si) wafers, we developed a differential method and studied its performance. To distinguish COPs from LPDs, we compared the difference in LPD properties before and after SC-1 cleaning. COP is defined as an LPD whose location does not change and becomes large in size after SC-1 cleaning. COPs obtained by the differential method were directly observed by atomic force microscopy (AFM) and the accuracy of counting COPs was estimated. Under optimum conditions, COP detection exceeded 75%, making the differential method useful for the estimation of COPs in CZ-Si wafers.