LibreOffice vs ONLYOFFICE on Linux — The Difference That Actually Matters Is the Document Engine, Not the Feature List
LibreOffice vs ONLYOFFICE on Linux — The Difference That Actually Matters Is the Document Engine, Not the Feature List
A real-world finding from switching to CachyOS as a daily driver: why one suite broke header images and the other didn't — and what that reveals about cross-platform document compatibility on Linux.
This is a follow-up to the first article in this series, which covered a three-iteration Windows → Linux migration on a custom desktop PC. Once CachyOS was running as a daily driver, one of the first practical questions was which office suite to use. The answer turned out to be more architecturally interesting than expected.
The standard advice for office suites on Linux is "use LibreOffice — it's mature, it's free, it's in every distro's repository." That advice isn't wrong. But it turns out to be incomplete in a way that matters a great deal if your documents regularly cross the Windows/Linux boundary — which, on a dual-boot machine, they do constantly.
The finding that prompted this comparison was specific: opening a document with images anchored inside headers produced a perfectly rendered file in one suite and a broken layout in the other. The feature lists of both suites are long and roughly comparable. The reason one handled the file correctly and the other didn't has nothing to do with features — it's architectural, and it goes all the way down to how each suite reads a .docx file.
1. The document engine — why it matters more than the feature list
Most office suite comparisons focus on what each application can do. This one starts with something more fundamental: how each application reads and writes a .docx file. The difference is not a minor implementation detail — it explains almost every cross-platform compatibility issue you will encounter.
LibreOffice — the translation engine
LibreOffice is built natively on the OpenDocument Format (ODF) ecosystem. Its internal document object model thinks in ODF terms — the open standard used by .odt, .ods, and .odp files. When you open a .docx file, LibreOffice dynamically translates Microsoft's proprietary XML styling tags into ODF equivalents in memory. When you save, it translates back.
Complex formatting that doesn't have a clean ODF equivalent — like an image anchored precisely inside a header grid — can be lost or miscalculated during this round-trip translation.
This translation works well for simple documents. For complex anchor placements, precise header/footer layouts, or formatting that relies on OOXML-specific properties, the round-trip introduces the risk of subtle or not-so-subtle breakage. It's not a bug in LibreOffice — it's an inherent consequence of the translation architecture.
ONLYOFFICE — the native OOXML engine
ONLYOFFICE takes a fundamentally different approach. Its entire document object model was written from scratch using Microsoft's Office Open XML (OOXML) standards natively. When you open a .docx file, ONLYOFFICE parses the XML directly with no translation layer — it reads the same format Microsoft Word writes, using the same structural model.
No translation. What ONLYOFFICE renders on screen is structurally identical to how the file is stored — and to how Microsoft Word would render it.
The practical result: formatting that lives inside the OOXML structure — image anchors, header layouts, table cell properties, paragraph spacing — is preserved exactly. The suite doesn't need to find an ODF equivalent for every property because it never leaves the OOXML world.
The insight in one sentence: If your documents regularly cross between Windows and Linux — as they do on a dual-boot machine — the choice of office suite is really a choice of document engine. A suite that reads OOXML natively will preserve your formatting; a suite that translates it may not.
2. Performance on CachyOS specifically
CachyOS is tuned for raw execution speed — advanced CPU instruction sets, custom kernel schedulers, and packages compiled with optimisations not present in generic distro builds. How each office suite benefits from this depends on how it's packaged and what its engine is built from.
| Metric | LibreOffice (libreoffice-fresh) | ONLYOFFICE (onlyoffice-bin) |
|---|---|---|
| Package type | Native Arch compilation | Pre-compiled upstream binary (-bin) |
| Instruction optimisation | High. Compiled locally — leverages CachyOS system optimisations and native C++ shared libraries. | Moderate. Pre-compiled upstream x86-64 binary — efficient due to its JS/C++ hybrid engine, but doesn't benefit from CachyOS-specific compilation. |
| Memory footprint | Low-to-moderate. Fast cold starts. | Slightly higher initial RAM — single-engine tabbed interface loads more upfront. |
| UI integration | Seamlessly hooks into Qt6/KDE or GTK/GNOME system themes. | Custom unified web-tech layout engine. Requires manual toggling for native window borders. |
| CachyOS advantage | Higher — benefits from local compilation and system optimisations. | Lower — pre-compiled binary doesn't adapt to CachyOS-specific tuning. |
3. Feature depth vs workflow scope
The two suites are built around different philosophies, and understanding that difference is more useful than comparing feature counts.
Decades of deeply technical, power-user features across a full application suite: a vector drawing tool (Draw), an offline database manager (Base), a LaTeX-style equation editor (Math), and a presentation tool (Impress). It is a complete, air-gapped local workstation suite that operates entirely without a network connection or cloud dependency. If you need advanced mathematical typesetting, local database generation, or a drawing tool that rivals dedicated vector applications — LibreOffice has it.
Best inside an open-source ecosystem where documents stay in ODF format and don't need to cross to Microsoft Office users.
Focused entirely on the three core document types: Documents, Spreadsheets, and Presentations. Modern ribbon interface, document tabs, embedded markdown support, and clean formatting without the legacy toolbar aesthetic of default LibreOffice. It doesn't try to be everything — it tries to be a reliable, format-faithful replacement for Microsoft Office's core three applications.
Best when your documents regularly cross between Linux and Windows — or between Linux and Microsoft Office users.
4. The verdict — and when to use which
- Your workflow involves
.docx,.xlsx, or.pptxfiles shared with Windows users - Documents contain complex formatting — images in headers, precise anchor placements, table styles
- You're on a dual-boot machine where the same file opens in both OSes
- A clean, modern interface matters for daily use
- You work entirely in open formats (ODF) and don't share with Microsoft Office users
- You need advanced features: database management, vector drawing, mathematical typesetting
- System integration and native theming matter — it hooks into KDE/GNOME cleanly
- You want to maximise CachyOS's compilation optimisations
Use ONLYOFFICE as the primary suite for any document that crosses between Linux and Windows. Its native OOXML engine means the file on your shared drive looks the same whether you open it from CachyOS or from Windows.
Keep LibreOffice installed for its specialised tools — particularly Draw and Math — that ONLYOFFICE doesn't offer. They're not in competition for the same documents; they're complementary.
5. The dual-boot dimension — why this matters more than on a Linux-only machine
On a machine that runs only Linux, the office suite choice is simpler — you pick based on features and preference, and your documents stay in whichever format you choose. On a dual-boot machine, the documents on your shared drive are opened from both operating systems. That changes the calculus significantly.
A .docx file on a shared NTFS drive might be:
- Created on Windows, opened and edited on Linux
- Created on Linux, sent to someone using Microsoft Office
- A template with complex formatting that needs to look identical on both sides
In all three cases, a suite that translates OOXML to ODF and back introduces risk at every open-edit-save cycle. A suite that reads OOXML natively removes that risk entirely.
- Store documents on the shared NTFS drive (accessible from both OSes)
- Use ONLYOFFICE on Linux — reads and writes OOXML natively
- Use Microsoft Office on Windows — reads and writes OOXML natively
- Result: the file is structurally identical regardless of which OS last edited it
This is the workflow that eliminated the header image breakage that prompted this comparison. The image wasn't broken by Linux, or by the filesystem, or by the transfer between OSes — it was broken by a translation step that ONLYOFFICE simply doesn't perform.
The takeaway
The office suite comparison that seems like a feature question is actually an architecture question. On a Linux-only machine in an open-source ecosystem, LibreOffice is the right choice. On a dual-boot machine where documents cross between Linux and Windows regularly, ONLYOFFICE's native OOXML engine removes an entire class of formatting problems before they start.
Part of the Linux daily driver series — findings from running CachyOS as a primary OS for research, creative work, and development.
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