Most of our software products are offered in two editions: Installer and Portable
Installer is an application packaged into an installation program (setup wizard). The installer places the application into a specific folder, customarily into "Program Files (x86)", creates shortcuts and adds an uninstaller. The installer may also register file associations and extra components in the system to enable additional functionality of the application. Installer usually requires administrator privileges.
Vovsoft installers are created using Inno Setup. It is an open-source setup creator for Windows programs. NSIS (Nullsoft Scriptable Install System) is also a good alternative.
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Portable application can be placed in any folder on your computer, a USB flash drive or other removable media and launched from there. Portable software creates configuration files in its folder and generally doesn’t change anything in the system it runs on. If you copy the configuration files together with the executable file to another media, all your settings will be carried across too.
Unless you have specific reasons to use the portable edition, it is best to use the installer to get the best of what the software has to offer.