Smart Update:
The Smart Update process comprises two components. First, it only overwrites files that have changed. The software will review the current version that is installed, and if a file is at the same level as the Product Update, it will not change it. This provides you with a smoother, faster install with less possibility for errors.
Many Sage ERP MAS 500 customers have made customizations to their software, and are reluctant to install Product Updates because they may inadvertently overwrite one of their customizations. The new Smart Update now checks all of the files it is going to overwrite to see if there are any customizations. If customizations exist, a window is displayed during the installation process. You will be able to view a list of the files that have been customized, and choose whether to overwrite them during the installation of the Product Update.
The new Smart Update process means that you can install Product Updates with confidence and quickly use the new features.
via: http://goo.gl/YR0H6