AutoCAD’s DWG Compare is the right tool when you own both revisions as DWG files: it overlays the comparison drawing on the current one in model space, colors what was added and removed, and wraps each change in a revision cloud. Most people who check revisions do not have the DWGs, though. Contractors, estimators, plan reviewers and print shops receive PDF sets, often plotted or scanned, and need to know which sheets changed. Drawing Revision Delta, a Windows app from Automata Labs, compares two whole PDF or scanned sets, matches sheets by their sheet numbers, ranks the most changed sheets first and exports a clouded PDF and a change report, with no AutoCAD and no upload.
This is a fair comparison of the two tools, based on Autodesk’s own documentation, so you can pick the one that fits the files in your hands.
Compare two PDF or scanned drawing sets on your own PC and see which sheets changed.
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What does AutoCAD DWG Compare do?
Autodesk’s help page, About Comparing Differences Between Drawings (DWG Compare), describes it this way. You run the COMPARE command in the current drawing and pick a comparison drawing. AutoCAD then shows the result in the current drawing:
- Objects common to both drawings in gray.
- Objects only in the comparison drawing in red.
- Objects only in the current drawing in green.
- Revision clouds around each change set, with arrow buttons on the DWG Compare toolbar to zoom from one to the next.
It works at the object level, so it knows that a line moved or a block changed rather than inferring it from pixels. You can import differences from the comparison drawing into the current one, and export the result to a snapshot drawing for reference. For two versions of the same drawing in a supported cloud account, Autodesk points to Activity Insights instead.
What are DWG Compare’s limits?
Autodesk lists them on the same page. The ones that matter most for revision checks:
| Limitation, per Autodesk | What it means in practice |
|---|---|
| Supports DWG files only | A PDF or scanned set cannot be compared |
| Operates in model space only | Sheet layouts, title blocks and paper-space notes are outside the comparison |
| Does not support all object types, including images, non-DWG underlays and point clouds | Raster backgrounds and PDF underlays are not compared |
| Cannot compare a result against a third drawing | Three-way checks need separate runs |
| Graphics display only in the 2D Wireframe visual style in AutoCAD | Comparisons are viewed in that style |
It also compares one drawing against one drawing. A 120-sheet set means opening and comparing each pair, and AutoCAD is sold as a subscription, per Autodesk’s AutoCAD page. For the architect or engineer who authored the set, that is fine: they have the files and the license. For everyone downstream, it is usually not an option.
What do you do when you only have PDFs?
Compare the sheets as issued. Drawing Revision Delta takes the earlier and the later set as folders or files and works through them as sets, not single drawings:
- Load both revisions. PDFs, scanned TIFFs and other images are accepted, and multi-page files are split into sheets.
- Pair the sheets. Sheets are matched across the two sets by the sheet number in the title block. When a sheet has no text layer, as with scans and many CAD plots, the app reads the title block with the text recognition built into Windows. You can correct any pair by hand.
- Align and compare. Each pair is aligned for shift, rotation and scale, then corrected locally for the slight stretch that different plotters and scanners introduce, and compared at the resolution and sensitivity you choose.
- Review the most changed sheets first. The Pairs table shows how much of each sheet changed and sorts the most changed to the top. Sheets that are new in the later set, or missing from it, are listed.
- Step through the changes. Overlay (red only in the earlier revision, blue only in the later one), Blink or Side by side, with revision clouds around each change. Where both PDFs have text, changed words are listed in plain terms, for example 2x6 to 2x8. A mask over the title block ignores date and revision-letter edits.
Rank every sheet by how much it changed, then step through the clouds sheet by sheet.
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How do the two tools compare side by side?
| AutoCAD DWG Compare | Drawing Revision Delta | |
|---|---|---|
| Input | Two DWG files | Two sets of PDFs, scanned TIFFs or images |
| Scope per run | One drawing against one drawing | Whole sets, paired by sheet number |
| What is compared | DWG objects in model space | Each sheet as issued, including layouts and notes |
| Scanned sheets | Not supported (images are an exception) | Supported; title blocks read with Windows OCR |
| Result | Colors and revision clouds in the current drawing | Overlay, Blink, Side by side, with revision clouds |
| Text changes | Object changes | Changed words listed where both PDFs have text |
| Exports | Snapshot drawing; import differences | Later revision with clouds as PDF markups, PDF change report with SHA-256 of every input, CSV lists, PNG snapshots |
| Licence | AutoCAD subscription | One-time purchase in the Microsoft Store |
| Best for | The team that authors the DWGs | Anyone who receives drawing sets as PDFs |
Neither tool replaces reading the drawings. Both show you where to look.
When is DWG Compare the better choice?
Use AutoCAD’s tool when:
- You authored the drawings and have both DWG revisions.
- You need object-level answers, such as whether a block definition changed or a dimension object was edited.
- You want to pull changes across with Import Objects while reconciling two versions.
Use a PDF set compare when:
- You received the set from the design team as PDFs, and the DWGs are not yours to ask for.
- The sheets are scanned or plotted without a text layer.
- You need the whole set ranked, so you can spend your review time on the five sheets that changed rather than the ninety that did not.
- You need a record, such as a clouded PDF for the field and a report with the hash of each input file for the project file.
Our guide on how to compare two drawing revisions covers the manual methods, and comparing scanned drawings to a CAD PDF covers mixed sets.
What about Acrobat and Bluebeam?
They sit between the two: both work on PDFs rather than DWGs. We have written fair comparisons of Acrobat Compare Files and Bluebeam Revu with Drawing Revision Delta. The question to ask of any PDF tool is pairing: when sheets are added, removed or reordered between revisions, Drawing Revision Delta matches them by sheet number, and lists new and missing sheets, before it compares anything.
Frequently asked questions
Can AutoCAD compare PDF drawings?
Not with DWG Compare. Autodesk’s documentation says it supports DWG files only and does not support images or non-DWG underlays.
Does Drawing Revision Delta need AutoCAD?
No. It works on PDFs and images on your own PC, with no account, no sign-in and no telemetry.
Does DWG Compare look at title blocks on layouts?
Autodesk says DWG Compare operates in model space only, and switches to the Model tab if a drawing was saved in a layout.
Can Drawing Revision Delta handle scanned sets?
Yes. Scanned TIFFs and other images are accepted, and title blocks without a text layer are read with Windows text recognition. You can correct any pairing by hand.
What does Drawing Revision Delta export?
The later revision’s sheets, unchanged, with a revision cloud around every change as PDF markups; a PDF change report with a SHA-256 hash of every input file; CSV files of sheets and changes; and PNG snapshots.
Try Drawing Revision Delta
Drawing Revision Delta is a one-time purchase in the Microsoft Store with a free trial. Compare the last two issues of a set you are working on and check the ranked list against what the transmittal said changed. More detail is on the Drawing Revision Delta product page.
Two revisions of a drawing set arrive. See which sheets changed and where, on your own PC.
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AutoCAD is a registered trademark of Autodesk, Inc. Acrobat is a trademark of Adobe, and Revu is a trademark of Bluebeam, Inc. Drawing Revision Delta is not affiliated with any of them.
Last updated 20 October 2026. Published by Automata Labs, a software company in Canada.