You can review differences between the current version and an earlier or later version of the same project in a detailed report.
On the Report tab, choose Compare Projects.
(In Project 2010, on the Project tab, in the Reports group, choose Compare Projects.)
Select the project version you want to compare from the drop-down list.
To locate project versions, choose Browse. You must log on to Project Server to open projects that are stored there. You can only compare project versions for which you have access permissions.
In the Task Table and Resource Table lists, select the tables that contain the data that you want to compare.
If you don't want to compare tasks or resources, select (None).
You can save the report for future reference.
The color coding and indicators for the comparison report are described in the Legend for Comparison Report pane on the left side of the screen.
A comparison report contains only the differences between the two versions. It is not a consolidation of the two projects.
This utility does not compare assignments. It compares tasks and resources only.