Data merge processing based on difference between source and merged data includes creating merged data from a source data records, the merged data including data fields, performing a difference determination as between the merged data and the source data records, the difference determination including, for each source data record of the source data records, comparison of data in data fields of the merged data to the source data record, and performing processing with respect to the merged data based on the difference determination. Performing processing can include aborting a merge operation to save a merged data record with the merged data, or storing and maintaining a merged data record including the merged data, based on the difference determination determining, for each source data record of the source data records, that the degree of difference between the merged data and the source data record does not exceed a threshold.