How to Compare Word Documents Side by Side.
- Open the documents you want to compare side by side.
- On the Window menu, click Compare Side by Side with.
- On the Compare Side by Side toolbar, do any of the following:
- If you want to scroll through the documents at the same time, click Synchronous Scrolling
- If you want to reset the document windows to the positions they were in when you first started comparing documents, click Reset Window Position
- Click Close Side by Side to stop comparing documents.
Note If you open two documents, the command on the Window menu will include the file name of one of those documents. For example, if you open “document1.doc” and then “document2.doc,” the Window menu shows the command as Compare Side by Side with document2.doc.
Read more here.