|Tools / Comparing and Merging Documents|
The Compare Files tool can be used to compare files or XML file fragments. To compare two files side by side, open the Diff Files dialog from . Using the browse drop-down list, open a file in the left side of the dialog, and the file you want to compare it to in the right side. To highlight the differences between the two files, click the Perform File Differencing button. The line numbers on each side help you to quickly identify the locations of the differences.
To compare XML file fragments, you need to copy and paste the fragments you want to compare into each side, without selecting a file. If a file is already selected, you need to close it, using the Close (Ctrl+W (Command+W on OS X)) button, before pasting the fragments.
You can edit both the source and the target file. The differences are refreshed when you save the modified document.
The Compare Files Window
Adjacent changes are grouped into blocks of changes. This layout allows you to easily identify and focus on a group of related changes.