They’re the same… except when they’re not.
Unfortunately, the file extension alone doesn’t tell me enough to make the decision between .msi and .exe formatted files. There’s a little more data needed before making the decision.
It’s about more than file formats; it’s about what those downloads do.
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Exe versus msi
.Exe files are executable programs, while .msi files install software using Windows Installer. If both are offered, they likely do the same thing. However, if the .exe is a portable version, it skips installation, offering on-the-go use. Choose based on your need for installation convenience or portability.
.Exe and .msi
.exe, for EXEcutable, is the most basic file format that contains Windows programs (also called apps or applications). Most (though not all) of the programs running on your machine start with an .exe file somewhere.
.msi, for MicroSoft Installer, is, as the name implies, an installation file. It contains information used to install a software package in Windows. While not technically a “program”, it certainly behaves like one. It can be something you “run” in order to begin the installation process. The program that processes the instructions is the Windows Installer service, which is part of Windows itself.
.Exe or .msi?
If you’re given the option of either an .exe or a .msi in order to install a program, they’re probably going to do the exact same thing. In fact, it’s likely that the .exe actually contains an .msi, which is extracted and then passed on to the Windows Installer service.
It’s rare, though, that you would be given the choice of a .exe or a .msi to do exactly the same thing. There’s no real advantage of one over the other if both are available. Typically, only one will be offered.
Unless there’s a difference.
.Exe only
If you’re offered only a .exe file to set up a program, it could be an .msi contained within an .exe, as I described above. Run it and you set up the program.
It could also be a setup program that doesn’t use Windows Installer at all. While application vendors are encouraged to standardize the use of Windows Installer, they’re not required to. There are many installation toolkits that can be used instead.
The one characteristic they share is that almost all begin by running an .exe — often setup.exe.
.Exe as an alterative
If you’re presented with both an .msi and an .exe for download, there’s probably an important difference between the two.
The .msi installs the software on your machine. That means putting all the right files in all the right places as well as adding or modifying registry entries and possibly other things.
The .exe, on the other hand, is likely to be a “portable” version of the application. By that I mean there’s no setup involved at all. The .exe is the program. To run the program, you run the .exe and nothing more.
That’s the missing piece of data. When this is the case, the download page will indicate that this is the portable version. Your choice of .msi versus .exe is really a choice between installing the software regularly or not installing it at all but running it directly.
Portable?
In addition to the lack of an installation process, differences between regular (.msi) and portable (.exe) versions include:
- Portable versions are not added to your Windows Start menu.
- Portable versions usually don’t1 keep settings in the Windows registry. Some may keep settings and other information in local “.ini” files; others simply don’t keep any of that information at all, starting with a clean slate each time you run the program.
- Portable versions typically run well from USB sticks or networked media. This is where the name “portable” comes from, as you can take a USB stick from machine to machine to run the software.
- Some portable versions don’t auto-update. Some may tell you there’s an update available, but it’s up to you to download the update and replace the version you have.
Do this
If you’re offered both and they’re truly the same thing, it doesn’t matter whether you choose .exe or .msi. .Msi might be a tiny bit smaller or faster, I suppose, since it won’t have the .exe overhead of extracting the .msi to initiate the setup.
If you’re offered an .msi setup and an .exe portable, as is more likely, then the decision depends on what you’re attempting to do. I tend to run the installer so as to have everything clearly set up and the program added to my Start menu. That being said, I also have .exe utilities that are portable simply because they’re small, I use them on multiple machines, and there’s really no advantage to running setup.
The choice is yours.
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Footnotes & References
1: I have to say “usually” don’t because of course they could. It’s bad behavior for a portable program, though, as it violates one of the reasons for it to be portable.
