SSP can have an edge and DAP in the soil is

SSP can have an edge and DAP in the soil is Deficient in S.
SSP is the most popular phosphatic fertilizer after DAP and it contains 3 major plant nutrients namely Phosphorus, Sulphur, and Calcium along with traces of many micro-nutrients.
DAP is Diammonium phosphate, it is a series of water-soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid.
SSP can have an edge in supplying Sulphur as it provides Sulphur also as a nutrient whereas DAP does not provide Sulphur to the soil thus it makes soil deficient I Sulphur.