What is the difference between the MSI file and .EXE file?

MSI (Microsoft Installer) allows install, uninstall and repair the program with a single file, while .EXE file needs two files to install and uninstall the software. Also,.EXE file is able to detect the existing version of the software and give option to user to uninstall the program while MSI will instruct the users to use the add and remove program in control panel to remove the existing product first and then you can install the new program.