Context and nuance are very important. Are the allied forces of WWII all mass murderers? Or to put it more broadly what distinguishes a soldier who has killed

Context and nuance are very important. Are the allied forces of WWII all mass murderers? Or to put it more broadly what distinguishes a soldier who has killed dozens of enemy soldiers from a school shooter who killed dozens of his peers? According to your statement they are morally equivalent, society at large would vehemently disagree with you.