In many cases we have to compare two Word documents, having them side by side is vital for comparison. You could open both the documents in separate windows and snap them in Windows 7, but this is a time consuming task. You can place two documents side by side within a single window without the fuss using Word 2010′s build-in feature.
First of all be sure to open both the documents that you wish to compare. Once done, go to any one of them and navigate to the View Tab on the ribbon.
Now under the Window section, select the View Side by Side option.