Compare FSX vs FS2004 for graphics, performance, add-ons and modern Windows compatibility, then choose the right legacy Microsoft flight simulator.
For most simmers, FSX: Steam Edition is the better legacy Microsoft flight simulator: it offers richer default aircraft and scenery, missions, broader later-generation add-on support and fewer disc-era installation problems. Choose FS2004 (FS9) instead when a favourite aircraft or scenery requires it, or when very low hardware demand matters most.
Which one should you choose?
Choose FSX for a new general-purpose installation; choose FS2004 for a specific FS9-only setup. The age difference matters less than your required add-ons, computer and tolerance for troubleshooting old software.
- Use FSX: Steam Edition if you want the easiest FSX installation, missions, improved default visuals, SimConnect-based utilities and access to the larger later-generation add-on ecosystem.
- Use boxed FSX if you already own it and depend on an older product that explicitly requires that edition. Our comparison of how Steam Edition differs from boxed FSX in installation and legacy support covers that choice separately.
- Use FS2004 if an irreplaceable aircraft, panel, scenery package or virtual-airline setup was built only for FS9, or if you value high frame rates on limited hardware over newer effects.
A mistake we see constantly is choosing FS2004 because it appears faster, then discovering that the required utility was only made for FSX. Start with the aircraft and scenery you intend to use, not a comparison of default frame rates.
How do FSX and FS2004 differ?
FSX is the more capable platform, while FS2004 is lighter and often simpler to tune.
| Area | FS2004 | FSX |
|---|---|---|
| Graphics | Simpler terrain, autogen, water and virtual cockpits | More detailed world rendering, water effects, ground traffic and virtual cockpits |
| Default flying | Free Flight, lessons and traditional flights | Free Flight and lessons plus a substantial mission system |
| Performance | Lower hardware demand and usually higher frame rates | More CPU-intensive, particularly with dense scenery, traffic and weather |
| Add-on platform | Large FS9-era library using older gauges, modules and installers | Large library with SimConnect support and more later-generation utilities |
| Memory | 32-bit, but its lighter content can leave more headroom | Also 32-bit and more prone to memory pressure in heavily modified installations |
| Best fit | Preserving a specific classic setup | Building the most versatile legacy Microsoft simulator |
Neither simulator behaves like a modern 64-bit platform. High-resolution textures, detailed airports, complex aircraft and heavy AI traffic can still produce out-of-memory crashes, especially in FSX. A powerful graphics card also cannot remove every bottleneck because both simulators rely heavily on main-thread CPU performance.
Can FS2004 add-ons be used in FSX?
FS2004 add-ons are not automatically compatible with FSX, even when an aircraft initially appears to load.
The simulators use different aircraft folder structures, model features, gauges, scenery compilers and module interfaces. A basic texture or uncomplicated scenery package may be adaptable, but panels can appear blank, animations may fail and airport elevations or exclusions can be wrong. Copying an entire FS2004 Aircraft folder into FSX is not a dependable conversion method.
Check that each download explicitly names your simulator. Our library separates FS2004-specific freeware aircraft and scenery from FSX aircraft, scenery and utility downloads, which helps prevent installing the right add-on into the wrong simulator.
FSX editions create another compatibility check. Most conventional aircraft and scenery can work in Steam Edition, but installers, DLL-based utilities and products that search for boxed-FSX registry entries may require special handling. Check which boxed-FSX add-ons normally transfer to Steam Edition before committing to an old collection.
Which runs better on a modern PC?
FS2004 generally produces higher frame rates, but FSX: Steam Edition is usually easier to establish on a modern Windows computer.
FS2004 and boxed FSX can encounter disc checks, old installers, protected-folder permissions, obsolete runtime dependencies and gauges that modern security settings reject. Compatibility mode does not fix every one of these problems, and enabling several compatibility options at once can make diagnosis harder.
FSX: Steam Edition removes the physical-disc dependency and includes an updated FSX build with Acceleration content. It remains an old 32-bit simulator, however, so maximum scenery, autogen, road traffic and AI sliders can overwhelm it even when the computer is much newer than the software.
What is the safest way to build either installation?
A clean base installation followed by incremental add-on testing prevents most difficult FSX and FS2004 failures.
- List essential add-ons first. Confirm whether each one requires FS2004, boxed FSX, FSX: Steam Edition or a particular expansion.
- Use a suitable installation location. Where the edition permits it, avoid a heavily protected Windows program folder because old installers often need to write directly into the simulator directory.
- Apply the correct updates before add-ons. Bring FS2004 to its 9.1 update level and boxed FSX to its final appropriate service-pack or Acceleration level. Do not apply boxed-FSX service packs to Steam Edition.
- Run the simulator once. Let it create its configuration files, then add aircraft, scenery and utilities in small groups.
- Test after every change. If a crash begins, remove the last addition rather than reinstalling the entire simulator or replacing random DLL files.
The practical verdict
FSX: Steam Edition is the best choice for most people comparing FSX vs FS2004. It provides the strongest balance of content, add-on support and installation convenience. FS2004 remains the correct choice when a valued FS9-only aircraft or scenery collection is the whole reason for using a legacy simulator.
You can also keep FS2004 and FSX installed side by side. They use separate simulator and configuration folders, but their aircraft, gauges and scenery libraries should remain separate rather than being shared between installations.