The Variance column format is used by the standard Variance column in the Columns menu. It displays the difference between the values in two other columns, such as the Current and Previous columns. Whereas the standard setup displays both the value and percentage of the variance, when customizing this column you have the option to display the value only or the percentage only. You can also select the columns on which to calculate the variance.
Select the column you want to start with from the From list (this is the column from which you will subtract the other column).
Select the column you want to subtract from the Subtract list.
Select how you want to show the variance as: Value and percentage, Percentage only or Value only.