There are situations when you may need to navigate between two distinct folders with the same structure. Once the "Synchronized Browsing" is switched on, then navigating to a folder in the source panel will trigger the automatic navigation to that same named folder in the target panel.
This proves useful when you have the same folder structure for each project and you want to compare or copy files between two projects that are somewhere deep in the folder structure.
This feature runs hand-in-hand and compliments the ability to "Run External Diff".