If the dependency snapshot shown in the Architecture View differs from the current solution, the Show Diff button becomes available. When this button is off, you see the current state of the solution; when it is on, you see the state recorded in the snapshot plus the differences between the snapshot and the current solution state. The differences are highlighted as follows: the items (projects and references) that exist in the snapshot but are missing from the solution are highlighted in red, the items that exist in the solution but are missing from the snapshot are highlighted in dark green.
Saving and loading snapshots
If you want to record the current state of the solution, you can save the snapshot to a file. To do so, click Save Architecture Graph on the toolbar and choose where to save the snapshot file.
You can load and study the saved snapshot later event without opening the solution. If the solution is opened, you can see differences between current state of the solution and the state saved in the snapshot. To open a saved snapshot, choose ReSharper | Architecture | Compare With Saved.