xlCompare doesn't have Visual Basic editor like in Excel (You can open it by pressing Alt+F11 hotkey). So, there is no Project Tree and navigation a bit different.
All types of the VB Objects are on the View tab on the Ribbon
All types of objects you can select in the Project Tree in the Visual Basic Editor you can find here:
This works like a filter - you select Form Objects (like in this example) and all forms are on the tab strip on the bottom:
Browse Button [...] gives you complete list of the objects (Forms/Modules/Sheets).
When you select Form\Modules it's contents is reflected in the xlCompare window.