What should be the output of a function that calculates the weight difference (Diff) given two sample weights (S1 and S2)?

The output of a function designed to calculate the weight difference (Diff) given two sample weights (S1 and S2) should indeed be Diff because the purpose of the function is to derive the difference between the two weights. This value, Diff, represents the result of a specific computation intended to inform the user about how much S1 differs from S2, either positively or negatively.

In a typical implementation, the function would take S1 and S2 as inputs and perform a calculation such as Diff = S1 - S2 (or Diff = S2 - S1, depending on the desired interpretation of the difference). The significance of returning Diff is that it provides the actual result of the operation, which is what users need when they are interested in understanding the weight difference.

Returning S1, S2, or both would not fulfill the function's intent, as it would not provide the relevant information regarding the difference between those two values. Therefore, the function's design is correctly aimed at producing the difference, making Diff the appropriate output.