To understand the percentage difference between 100 and 75, we first need to understand what percentage difference means. Percentage difference is a way to measure the difference between two values as a percentage of one of the values. In this case, we are comparing 100 and 75.

To calculate the percentage difference between 100 and 75, we need to first find the absolute difference between the two values. The absolute difference is simply the difference between the two values without considering whether one is greater than the other. In this case, the absolute difference between 100 and 75 is 25.

Next, we need to find the average of the two values. The average of 100 and 75 is (100 + 75) / 2 = 87.5.

Finally, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 100 and 75 is:

|100 - 75| / ((100 + 75) / 2) * 100 = 25 / 87.5 * 100 = 28.57%

Therefore, the percentage difference between 100 and 75 is 28.57%. This means that 75 is 28.57% less than 100.