An executable file is only one part of an installed desktop application. Applications can also need libraries, assets, configuration, metadata and registration with operating-system services.

Self-contained bundles

A platform can package an application's files into one directory-like bundle containing executable code, resources and metadata. Installing can then be close to copying that bundle into an appropriate location.

Installers and system registration

Other application models place files in several system locations or register information such as file associations, services, uninstall data and shared components. An installer coordinates those changes and can reverse them later.

Platform conventions differ

macOS application bundles, Windows installers and Registry integration, and Linux package/desktop-entry conventions solve related problems with different contracts.

The important distinction is between building a runnable binary and integrating an application into a particular operating-system environment.