All Small Business Server 2011 versions are based on Server 2008 R2
The smallest version is the Windows Small Business Server 2011 Essentials. The server is designed for the use of Microsoft Online Services,
where, among other things, the e-mails are not stored directly on the local server, but in the cloud. The data is stored locally on the server.
There are 25 access licenses for the server, these cannot be extended. The user fees for the Microsoft Online Services are not included.
The standard version is called Windows Small Business Server 2011 Standard. This server is the normal SBS, which already existed in the 2003 and 2008 versions. The server is designed for up to 75 users with 5 licenses included.
For the small business server standard, there is a premium add-on, which includes a 2nd Windows Server 2008 R2 standard and SQL Server 2008 R2 for small business.
The Small Business Server All in one includes the SErver 2008 R2 functions as well as the Exchange Server 2010, Share Point Foundation 2010 and the Windows Server Update Services.