Heya buddy,
I've only a few hours interaction with VMWares EXSi and the rest.
As I understand it, ESXi5.+ is just the hypervisor as a standalone product, what you would do is use the Client, install and VM with windows or whatever server, then install vSphere which actually contains the SingleSignOn(SSO) WebClient and a few other products..
I think this answers what you are asking, I'm no pro by anymeans buddy 
Hope this helps
Kind regards,
D1DG3