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krishna@alight
krishna@alight
Participant
May 22, 2026
Question

PDF Compare Showing Same Text as Inserted and Deleted – Why is this happening?

  • May 22, 2026
  • 1 reply
  • 13 views

Hi Experts,

I am currently evaluating the Compare Files feature in Adobe Acrobat (for a POC), and I’ve encountered an issue that I’m not able to understand clearly.

During comparison, Adobe is flagging certain content as both “Text Inserted” and “Text Deleted”, even though the text appears to be exactly the same in both versions of the document.

Example (from comparison report):

  • Text Inserted:
    "V000001 JANE DOE016200010 DO NOT MAIL MONTREAL-OUEST QC H4X 1N4"

  • Text Deleted:
    "V000001 JANE DOE016200010 DO NOT MAIL MONTREAL-OUEST QC H4X 1N4"

As shown above, both strings are identical, yet the tool is treating them as changes.

Observation:

  • No visible difference in text content
  • However, other changes like font (ArialMT → Arial), font size (11 → 10), and color changes are also present in the comparison
  • This behavior is being reported alongside actual formatting changes

Questions:

  1. How does Adobe Acrobat internally validate text differences in Compare Files?
  2. Are there known limitations or settings that could help ignore such false positives?

Context:

This analysis is part of a PDF comparison tool evaluation (POC), so understanding this behavior is critical in determining accuracy and reliability.

    1 reply

    T
    Community Manager
    Tariq Ahmad DarCommunity Manager
    Community Manager
    May 22, 2026

    Hi ​@krishna@alight,

     

    This is expected behaviour, not a bug — and it comes down to how Acrobat reads a PDF internally.

     

    Acrobat's Compare Files engine does not compare raw text strings. It compares styled text runs — the atomic unit of text in a PDF content stream, where character content, font name, font size, and colour are all bundled together as a single object. When any of those attributes change, the entire run is classified as changed, even if the visible text is identical.

    In your case, the font change (ArialMT → Arial) and size change (11pt → 10pt) between the two documents are enough for the engine to classify the old run as deleted and the new run as inserted. The comparison report then displays the text content of each run — which happens to be the same string — giving the appearance of a false positive. It isn't one: the styled run genuinely changed.

    A couple of things worth knowing for your POC:

    The "Compare Text Only" checkbox in Settings is designed to ignore graphic and image differences, not font or size changes within text runs — so it won't filter these out. The filter dropdown in the results panel is more useful: it lets you isolate text, formatting, images, and annotations separately, which will help you assess the volume of formatting-only changes versus actual content changes.

    The practical interpretation rule for your evaluation: when "Text Deleted" and "Text Inserted" show the same string, that entry represents a formatting-only change. Actual text changes are entries where the two strings differ.

    If your POC requirement is strictly character-level text comparison with formatting ignored entirely, that is outside the design scope of Compare Files. For that use case, extracting the text layer from both PDFs and diffing programmatically would be the appropriate method.

    Full documentation on Compare Files settings: https://adobe.ly/4dFGOTd


    ~Tariq

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