Virtual Appliance -we can use only Vcenter (In build)
VDI-Virtual Desktop infrastructure
Connection server -We have to install OS(Windows 2008) and top of that we need to install connection server .
Basically structure is below :
Hardware ->Hypervisor->one virtual machine with OS 2008 for Vcenter and
One virtual machine OS (2008 server) and need to install connection server
Hardware ->Hypervisor -->Virtual appliance ->One virtual machine with windows 2008 and top of that we need to install connection server .,