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 12 and 16 is 4.

Next, we need to find the average of the two numbers, which is (12+16)/2 = 14.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100.

So, the percentage difference between 12 and 16 is (4/14) x 100 = 28.57%.

This means that the difference between 12 and 16 is 28.57% of their average value.