Working with Plan Diagrams
Query Profiler allows you to examine plans of different queries in a single view. For this, hold the CTRL key and select several plan diagrams in the query profiling tree.
You can set a number of plans that you want to compare with the most recent result. For this, click 
and then select a required number.
The following picture demonstrates that the Compare last two results option is selected. In this case, when you modify a query and then click 
the Get New Results button, the most recent result will be automatically compared with Plan #2.
Plan #1 does not participate in comparison.
To zoom in and out a pan diagram, right-click the plan diagram and then click Zoom.