It is not the difference between low/non fat and whole milk, it is the difference in how it is prepared. This horizon milk to be kept in the pantry and not refrigerated would have to be radiated or go through some other process of killing off all the bacteria, which would mean you could keep it on the shelf for several months without it going bad, regardless of its fat content. The Tuscan stuff looks like just your typical 1 gallon of milk, which when left out of the cold for even a few hours can turn sour, even if it is reduced fat or skim milk.