The vSphere Client is a new HTML5-based client that ships with vCenter Server alongside the vSphere Web Client. The new vSphere Client uses many of the same interface terminologies, topologies, and workflows as the vSphere Web Client. However, the vSphere Client does not support vSAN. Users of vSAN should continue to use the vSphere Web Client for those processes.
Not all functionality in the vSphere Web Client has been implemented for the vSphere Client in the vSphere 6.5 release. For an up-to-date list of unsupported functionality, see Functionality Updates for the vSphere Client Guide at http://www.vmware.com/info?id=1413.