Other than Entourage 2001, the rest of Microsoft's office productivity suite for Mac OS has always been consistant in using the same naming convention as their Windows platform counter-part. i.e. MS Word, MS Excel & MS Powerpoint. The naming for MS Office for mac platform is also "n+1" i.e. MS Word 2001 vs MS Word 2000, MS Excel 2008 vs MS Office 2007. Thus, now MS Office 2011 (Mac) vs MS Office 2010 (Windows)
Even though the mac office suite offering is from Microsoft, there are occasional incompatibility like differences in font-type causing slight misalignment of documents & email attachment ("winmail.dat" encoding issues). Also, it's an extremely tedious affair migrating windows Outlook ".PST" files to Entourage for mac.
With Outlook 2011 for Mac, now all the Windows users can export their mail data to the Mac platform with ease...
Reference from Wikipedia on the various edition for the Mac Platform:
Two editions are available to the general public. Home & Student provides Word, Excel and PowerPoint, while Home & Business adds Outlook and increased support. Microsoft Messenger 8 is included with both editions, and Microsoft Communicator for Mac 2011, which communicates with Microsoft Lync Server, is available only to volume licensing customers. Office 2011 requires an Intel Mac running Mac OS X v10.5.8 or higher.
Have you gotten a copy of the new version yet? Feel free to share your feedback on your experience...