Note, this is an Enterprise feature.
You can compare the latest unsaved changes to any previous project revision using the standard Compare Revisions feature in SqlDBM.
First, perform some changes to your project without saving. Whenever there are any unsaved changes, you will notice an asterisk next to the project name and revision at the top of the screen.
To compare these unsaved changes, click on the "Compare Revisions" from the left pane.
To compare the unsaved revision, select it along with a previous revision to compare to.