The update to Office for Mac 2011 additionally contains a range of bug fixes:
The 2008 update contains only the security fix. In both cases, you need to be running the most recent version of the software. To check this, go to the Help menu in any Office app and click Check for updates.Contacts that were created in x500 format did not work in Outlook for Mac
BCC recipient was missing on Gmail IMAP draft message in Outlook for Mac
Some contractions were marked as spelling errors in Outlook for Mac
Shared folders could not open other mailboxes that used Kerberos protocol in Outlook for Mac
Coordinated Universal Time was not included when you created a calendar event in Outlook for Mac
Fixes an issue in which OAB was not updated correctly for certain Office 365 users.
Fixes an issue that occured when you ran a Macro that contained "Applications.Dialogs(xlDialogSaveAs).Show."
Scrolling when Track Changes default settings are enabled in larger documents crashed Word for Mac
Transitions had graphic issues during slide shows in PowerPoint for Mac
Article Link: Microsoft Issues Security Updates for Office for Mac 2008 and 2011