We have a detailed explanation the description field: "As of January 2019 Bosch is no longer supplying ZR5TPP33S. It has been replaced by ZR5TPP33. The spark plug specs between ZR5TPP33S and ZR5TPP33 are identical making one plug work for both N55 and N63 applications." One plug is not newer than the other, they carried different applications. Ultimately, the only technical difference between these two plugs was the radio suppression noise specification which was more or less the same.