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 320 and 480 is 160 (480 - 320 = 160).

Next, we need to find the average of the two numbers. The average of 320 and 480 is (320 + 480) / 2 = 400.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 320 and 480 is (160 / 400) x 100 = 40%.

Therefore, the percentage difference between 320 and 480 is 40%. This means that the second number (480) is 40% larger than the first number (320).