vSphere Client - new version of the HTML5-based vSphere Client that will run alongside the vSphere Web Client. The vSphere Client is built right into vCenter Server 6.5 (both Windows and Appliance) and is enabled by default.
vSphere Web Client - improvements will help with the overall user experience. (Home screen reorganized, Performance improvements, Live refresh for power states, tasks.)
VMware, vSphere/6.5, vSphere with Operations Management Enterprise Plus