To find the percentage difference between two numbers, we first need to calculate the absolute difference between them. In this case, the absolute difference between 250 and 205 is 45.

Next, we need to find the average of the two numbers. The average of 250 and 205 is (250+205)/2 = 227.5.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 250 and 205 is (45/227.5) x 100 = 19.78%.

Therefore, the percentage difference between 250 and 205 is 19.78%. This means that the difference between the two numbers is almost 20% of their average value.