What is the difference between Illustration Settings and a 'What If' scenario?

Illustration Settings is used to update the details of your Illustration. Updating this information will amend the original details of the illustration.

The 'What If' area allows you to create an alternative scenario that will sit alongside your original Illustration. This is great for comparing the details of the original scenario against your new 'What If' scenario. 

Once you are happy with the new scenario, you will need to enter the details into the Illustration Settings to update your Illustration.