Comparing PDF files with Acrobat Compare Files

Question

Regarding Acrobat Professional, the Compare Files function, I think it is an important function. However, some results appear out of order among the compared files. I would like to ask Adobe technicians if there are any improvements planned for this function? Or will we have to purchase other products (from third parties, such as InformIT) to compare files and/or content?

BaniVerma · Accepted Answer

Hi all,How do I get the most accurate results when comparing two PDF files?Acrobat's Compare Files tool analyzes two versions of a PDF and generates a report showing differences in text, images, formatting, annotations, and other document elements.For the best results:Open both PDF files in Acrobat.Select All tools > Compare Files.Choose the older and newer versions of the document.If you're comparing documents where only text changes matter, enable Compare text only.Select Compare to generate the comparison report.Reference:https://helpx.adobe.com/acrobat/using/compare-documents.htmlHow do I choose the appropriate document type?Before running the comparison, open Settings in the Compare Files window and select the document type that best matches your files.Document typeHow it comparesAutodetectAcrobat decides the document type for youReports, Spreadsheets, Magazine LayoutsCompares content as one continuous text body, end to endPresentation DecksCompares each slide or page as its own document, matching similar ones and identifying moved slidesScanned Documents, drawings, or illustrationsCompares an image capture of each page, pixel by pixel; useful for scans, images, or architectural drawingsTip: if your document content can reflow across pages, select Reports, Spreadsheets, or Magazine Layouts. Otherwise, select Presentation Decks.Reference:https://helpx.adobe.com/acrobat/using/compare-documents.htmlWhat can Compare Files identify?After comparing two PDFs, Acrobat generates a report that can identify differences in:TextImages and graphicsFormattingHeaders and footersAnnotationsBackgroundsNote: by default, annotation, formatting, and background differences are turned off in the report. To see these changes, select them from the Filter menu in the comparison toolbar.Referenceshttps://helpx.adobe.com/acrobat/using/compare-documents.htmlhttps://www.adobe.com/acrobat/features/compare-pdfs.htmlThanks,^BS

AnandSri · Answer

Hello @nelson_fachel!

I hope you are doing well, and thanks for reaching out.

Could you please share more details about the issue you are experiencing with the compare functionality? When you mention that the results seem out of order among the compared files, are you referring to all the files or just specific files with large images or content? Does it happen on a Windows machine or a Mac?

The Compare Files tool in Acrobat relies heavily on the underlying tag structure and reading order of the PDF. If:

The PDFs were created using different tools (e.g., Word vs. InDesign vs. scanned files),
The files have complex formatting (multi-column layouts, floating elements),
Or the documents lack proper accessibility tags (tagged PDFs),

Then Acrobat may not be able to correctly determine the intended order of the content, leading to misaligned comparisons or changes appearing out of sequence.

Additional Technical Causes:

OCR issues: If one of the files is scanned and OCR’d, inaccuracies in text recognition or bounding boxes can throw off the alignment.
Hidden metadata or artifacts: Invisible elements (like hidden form fields or annotations) may affect how Acrobat interprets changes.
Font encoding mismatches: Custom-encoded fonts may appear identical visually but differ at the text layer, confusing the comparison tool.
Different version histories: PDFs generated from templates or drafts may contain residual elements that impact structure.

What you can try:

Use “Compare by Appearance” (vs. Text)

In the Compare Files dialog, try toggling between “Compare Text Only” and “Compare Appearance” depending on the document type for better accuracy.

Optimize source PDFs before comparing

Use Preflight to flatten transparency, normalize fonts, or tag text properly.
Save PDFs as “Optimized PDFs” with a clean structure.

Break long documents into sections

For large reports, compare smaller sections (chapters or modules) to reduce layout-based misalignments.

To learn more about the Compare files in Acrobat, please see this article: https://adobe.ly/4j8DtwA

We're here to help, just need more info.

Thanks,

Anand Sri.

Document type	How it compares
Autodetect	Acrobat decides the document type for you
Reports, Spreadsheets, Magazine Layouts	Compares content as one continuous text body, end to end
Presentation Decks	Compares each slide or page as its own document, matching similar ones and identifying moved slides
Scanned Documents, drawings, or illustrations	Compares an image capture of each page, pixel by pixel; useful for scans, images, or architectural drawings

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