To Calculate the Difference in the Areas of Elements and Place as Text

Select the Area Calculator and Place Text tool (Drawing > Analyze > Area tools).
The Area Calculator and Place Text tool setting window opens:
Select the Green Plus button.
Select the first element (the element from which area is to be subtracted) and enter a data point to accept.
The element will be highlighted in green color. The area of the element will display at the top section of the tool setting window.
Select the red Minus button.
Select the second element (the element whose area is to be subtracted from the first element) and enter a data point to accept.
The element will be highlighted in red color. The difference in areas will display in the top section of the tool setting window.
Select the Place Text button.
Enter a data point where you wish to place the area text.
The difference in the areas of both the elements will be placed in the design.

Note: You can select multiple elements to find the difference of their areas.