Through View Side by Side feature you can instantly open up two document and take a look at both documents in Word 2010 simultaneously. It eventually provides an excellent way to compare two opened documents, adding more to it for convenience, you can also synchronizes the scrolling, i.e, on navigating through one document the other opened document would emulate the exact navigation.
Launch Word 2010 and open two documents to view them side by side.
Now from any document window, navigate to View tab and click View Side by Side.
Upon click it will open both Word document windows, now for generic comparison purpose, click Synchronous Scrolling.
On scrolling down the window, you will notice that scrolling is now synced with the other document. On scrolling up/down a document window, other document will automatically be scrolled in the same same way.
Just click Reset Window Position to reset the original position of both document windows.
You can also check out previously reviewed guides on How to Insert and Embed Excel spreadsheet in Word 2010 & Inserting Line Number in Word 2010.