It is designed for comparing text in large documents (250 pages or more).

Note: The text option can be used with any document type. Show in Report, select the elements of the documents for which you want to see the differences in the compare report.The differences (both text and line art and images) are combined into a single results document. The artwork is compared separately in the background. In documents containing magazine advertisements that have text on top of background image art, a reflowed passage is compared in text-only mode. With Scanned Documents selected, the text is compared separately from the graphics, and then the results are combined.With either the reports or presentation options selected, the Compare Text Only option identifies only the text differences between two documents.For comparing scanned files, select Scanned documents, drawings or illustrations. Tip: If your document content can reflow across pages, select Reports, spreadsheets, magazines layouts otherwise select Presentation Decks. This option is useful for comparing images or architectural drawings. It also identifies pages that are in a different order. Looks at each scanned page and matches ones that are similar.

Scanned Documents, drawing or illustrations: Creates an image capture of each scanned page and compares pixels.Identifies documents that have moved, such as slides in a presentation. Then compares the content of each matching document. Presentation Decks: Looks at each slide or page as a mini-document, and matches ones that are similar.Reports, Spreadsheets, Magazine Layouts: Compares the content as one continuous text body, from end to end.Select Autodetect to let Acrobat decide.

Under Document Description, select the type of documents that you are comparing.

You can limit the comparison to a portion of the documents by entering the page numbers in the Old File and New File fields.

Notepad ++ compare two files