vSphere Essentials and Essentials Plus are designed especially for small organizations just getting started with virtualization. Both provide virtualization and centralized management for up to three server hosts. vSphere Essentials provides server consolidation to help you get the most out of your hardware. Essentials Plus adds features such as vSphere Data Recovery for agent-less backup of your data and virtual machines. It also includes business-continuity features such as vSphere High Availability—for automatic restart of your applications when server failures are detected—and vSphere vMotion, to completely eliminate planned downtime for server maintenance.
sources : http://www.vmware.com/files/pdf/products/vsphere/VMware-vSphere-Essentials-DataSheet-DS-EN.pdf