– Larger virtual machines (up to 64 virtual CPUs (vCPUs) and 1TB of virtual RAM)
– New features in the virtual machine format version 9
– Flexible, space-efficient storage for virtual desktop infrastructure (VDI)
– vMotion (zero-downtime migration) without the need for shared storage configurations
– vSphere Data Protection is now based on EMC Avamar technology
– vSphere Replication enables efficient array-agnostic replication of virtual machine data over the LAN or WAN
And many new features targeted for the public and private cloud implementation.
Read the full list on vmware.com, and also you can take it for a spin at https://my.vmware.com/web/vmware/evalcenter?p=vmware-vsphere51-ent