Threats Manager Studio (TMS) includes functionality to evaluate differences between the current Threat Model, and another Threat Model or Template. This functionality is provided by the Merge tool, which allows not only to detect differences but also to selectively merge them with the current Threat Model.
To access the Merge tool, you need to open the Import ribbon and then to click button Merge Threat Models and Templates.
After having selected the Threat Model or Template to be used as the source for the comparison, you will be presented with the following interface. Of course, the target Threat Model for the comparison is the current one.
The Merge tool provides an interface to filter the items by specifying a part of their Name, and to show the items that are present only in the source, only in the target or different.
If you want to add a specific object, you can simply click on the related toggle in the Merge column.
The Merge tool categorizes the objects based on their type. If the source file is a Threat Model, then the types shown are more extensive than those shown for Templates: in fact, objects like entities, diagrams and Threat Events are not included in Templates, therefore it would not have sense to include them in the comparison.