The compare tool is basically used to find the changes between any two layers(you can even move the changes).
In your case as you moved all the changes from usr to var and you want to verify it which basically don’t need a compare tool
If you have many objects try to make project with filters to show the objects in usr layer(if everything is moved to var the project should not hold any objects). you can also make project from the model(this is for ax 2012)
If you want to check for a particular object , set the Application Object Layer to Show all layers from tools → options → development, now the object will show all the layers where it undergone modifications…