Comparison of key of the registry copy with current state of this key
You may compare any key from previously scanned copy of registry with its current state in the registry with the help of Compare with current registry button and menu item.
With all this going on the new scanning take place with creation of copy of this key (it will be written down into the RGF file), and then operation of comparing is going. If there are no differences, and you need not to store the newly scanned key, don't forget about Deleting Copies.