“Perspectives” is the name Eclipse gives to different window layouts.
The Debug perspective contains a layout optimized for debugging code such as Java. The FusionDebug perspective has been optimized for debugging ColdFusion applications.
You typically change to the FusionDebug perspective when you start a ColdFusion debugging session, and change back to an Editing perspective such as the CFEclipse perspective when you are writing code.
You can change perspective by selecting the Windows->Open Perspective menu option.