For years Citrix has a product to host applications from a centralized locations offering great flexibility and efficiency, called Citrix XenApp. In 2008 Citrix released XenDesktop, the VDI solution from Citrix. With this first release of XenDesktop it was possible to (only) publish a desktop hosted on a single user operating system (like Windows XP, Vista or 7).
Citrix has tried to choose an appropriate name for their products to help customers understand what product offers what solution (and reducing the ridiculous times they rename their products). Although this is an admirable attempt they failed to reach that goal.
A lot of customer assume that with XenApp they can (only) publish applications and with XenDesktop (only) desktops, how wrong can they be?