There is a single file that is the TinyTask program ("tinytask.exe") that is the self-contained 32-bit app. The various formats are different ways of packaging the same file. The "tinytask.zip" file just contains tinytask.exe in compressed form, which can be useful for environments where downloading executable files is blocked. Windows can natively extract this file by double-clicking it. The "tinytask_setup.exe" option is a standard Windows installation file. It installs TinyTask to its own Program Files folder and Start Menu app, optionally adds a desktop icon, and also includes an uninstall capability. This is the typical application package you would get for commercial software. The brilliant Inno Setup was used to create the install package, which TinyTask has supported with donations multiple times. If you're not sure which one to get, then the .exe download is the best choice.