This is a software compare tool that also can merge files and do compare folders, functionalities that can help upgrade source files.
You would be able to expand a subfolder, double clicking on anyone will generate a separate window where differences are viewed easily. Its “folder compare” will check and compare the subfolder tree inside each folder. The interface provides graphical views that help merging them without problems. You have two views of the two individual files and then on top a combined view of the two. You are, thus, able to view the merging for any problems. Software source merging is a specialized job and the tool reflects the same with an array of controls on the toolbar. This is a tool, obviously, for the specialist. You are also going to need some familiarity time.