This AddIn provides a single command button in the UI inside the Model workspace under the Inspect panel.

The functionality and description of the button changes depending on what it does.

When the command description is "Save Snapshot For Comparison" it saves the current model view by taking a snapshot of it - this will be the view we will be comparing to.

When the description is "Compare To Snapshot" it will take another snapshot and will bring up the default browser with a page where the user can switch between the previous snapshot and the latest snapshot to visually compare the changes in the model.

Also note that the second snapshot will be taken from exactly the same angle and with the same zoom factor as the first snapshot, thereby aiding the visual comparison.

The idea for this AddIn comes from this Idea Station post: Quick difference view between before and after an edit