Compare Documents in Acrobat

Acrobat 9 has a vastly improved Document> Compare Documents feature. Just select two PDFs, and Acrobat will display a copy of the newer PDF, with changed areas highlighted. It helps if you tell Acrobat what kind of document you’re comparing: page layout, illustration, or a scanned document.

Acrobat will show the newest version of the document, with changes highlighted. When you roll over a highlighted item or text, Acrobat displays a pop-up window that shows the older version of the content. Amazing.