You may experience unexpected results if you have third-party system software modiﬁcations installed, or if you've modiﬁed the operating system through other means.
Because of this, you may experience conflicts after doing a Software Update from Apple.
Note that an update's size may vary from computer to computer when installed using Software Update.
Also, some updates must be installed prior to others, so you should run Software Update more than once to make sure you have all available updates.
Standalone installer Download the update installer and run it manually.
This is a useful option when you need to update multiple computers but only want to download the update once.