To understand the percentage difference between two numbers, we first need to know what percentage means. Percentage is a way of expressing a number as a fraction of 100. For example, 50% means 50 out of 100 or 0.5 as a decimal.

Now, let's look at the percentage difference between 14 and 18. To find the percentage difference, we need to first find the absolute difference between the two numbers. Absolute difference means the difference without considering whether the numbers are positive or negative. In this case, the absolute difference between 14 and 18 is 4.

Next, we need to find the average of the two numbers. The average of 14 and 18 is (14+18)/2 = 16.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 14 and 18 is:

|14-18| / 16 x 100 = 4/16 x 100 = 25%

Therefore, the percentage difference between 14 and 18 is 25%. This means that 18 is 25% more than 14 or that 14 is 25% less than 18.