Microsoft SBS Server Editions :
Windows Small Business Server 2011 (SBS 2011) comes in two editions: Standard and Essentials. In addition, the Small Business Server Premium Add-on is available for SQL based line of business (LOB) support, or as an additional member server.
Small Business Server 2011 Standard
Your all-in-one network solution, designed and priced for small businesses with up to 75 users. SBS 2011 Standard delivers enterprise-class server technology in an affordable, all-in-one solution. SBS 2011 Standard helps protect your business information from loss by performing automatic daily backups. Additionally, it allows users to be more productive with features such as e-mail, Internet connectivity, internal websites, remote access, and file and printer sharing.
Small Business Server 2011 Essentials
Get ready for the future and take advantage of the cloud. Ideal as a first server for small businesses with up to 25 users, SBS 2011 Essentials provides a cost-effective and easy-to-use solution to help protect data, organize and access business information from virtually anywhere, support the applications needed to run a business, and quickly connect to online services for e-mail, collaboration and CRM.
Small Business Server 2011 Premium Add-on
The Windows Small Business Server 2011 Premium Add-On gives small businesses a flexible and cost-effective solution for deploying additional servers on a network running Windows SBS 2011. It provides a platform for running line-of-business (LOB) applications that are based on the SQL Server operating system, role-based server deployments (such as additional domain controllers), and virtual servers that run in a Hyper-V environment. It also gives you the flexibility to access a second application platform when you need it, yet requires minimal IT resources. Designed as an add-on component for Windows Small Business Server 2011 Essentials or Standard, Windows Small Business Server 2011 Premium Add-On includes Windows Server 2008 R2 Standard Technologies and SQL Server 2008 R2 for Small Business.