You can use the assign baselines feature to designate the current project or an existing baseline as the project, primary, secondary, or tertiary baseline. The project baseline or primary baseline can be designated as the project to use when calculating earned value
Open the project for which you want to select a project baseline. Go to Menu bar, Choose Project, Assign Baselines.
The primary, secondary, and tertiary baselines are user-defined baselines used to compare projects.
In the Project field: select the project to which you want to assign a project baseline.
In the Project Baseline field: select the desired baseline or the current project. If no baseline is designated as active, the current project is used as the baseline project.
Under User Baselines, choose an existing baseline or the current project.as the primary, secondary or tertiary baseline for a project from the drop down menu. You can compare up to 3 baselines at a single time, you can assign the same project as secondary and tertiary baselines.
Comparison with Baseline Schedules:
Open a layout showing current and baseline bars to identify tasks that start or finish later than planned. You can even modify the layout suiting your requirement for better comparison and save the layout for later usage, makes it easy to see variances between the current and baseline dates.