‎﴾ﷺ﴿ Vs عليه السلام
It’s just a convention, there’s no material difference between the two. Both are supplications for the prophets, and they loosely mean ‘ May the peace be upon him ‘ and ‘ May the peace and blessings of Allah be upon him ‘ respectively. If one chooses, theses supplications can be used interchangeably interchangeably. The choice of words is not important – what’s important is that the supplication be made from the heart rather than as a habit.