If you need to compare two PDF documents, there are two alternatives: you can either open two separate instances of your PDF viewer or use a dedicated tool to display the content side-by-side. One software utility that can help you out is Kiwi FREE PDF Comparer.
Written in Java and, therefore, platform-independent, this application makes it possible for you to browse the content of two PDF files at the same time and visually compare the content of the documents to spot differences.
The main window is split into two panels, each for a PDF document. Once the two files are opened, you can browse through pages, zoom in and out, and choose which pages Kiwi FREE PDF Comparer should look at.
There are two comparison modes you can choose from: Kiwi FREE PDF Comparer can either compare text or match pixels in images. Additional options allow you to configure how the application perceives text movements, insertions, and deletions, as differentiated, not differentiated or unchanged text.
The application highlights texts and images that do not match and help you identify text pieces or graphics that have been moved or deleted between two versions of the same file. Both PDF files may contain changes frames. The purpose is to compare the content and not format changes.
An application such as Kiwi FREE PDF Comparer can come in handy for repeated reviews of documents. Jumping from one difference to another is easily done, and changes are quickly spotted. And since the PDF format is one of the most versatile and, with a proper editor, any document can be saved as a PDF, it's safe to say you are able to use Kiwi FREE PDF Comparer to compare almost any two documents.