Technology categories that fall under application virtualization include:
Application streaming. Pieces of the application's code, data, and settings are delivered when they're first needed, instead of the entire application being delivered before startup. Running the packaged application may require the installation of a lightweight client application. Packages are usually delivered over a protocol such as HTTP, CIFS or RTSP.
Desktop virtualization is an umbrella term that describes software technologies that improve portability, manageability and compatibility of a computer's desktop environment by separating part or all of the desktop environment and associated applications from the physical client device that is used to access it. A common implementation of this approach is to host multiple desktop operating system instances on a server hardware platform running a hypervisor. This is generally referred to as "Virtual Desktop Infrastructure" or "VDI".
Remote Desktop Services is a server-based computing/presentation virtualization component of particular OS that allows a user to access applications and data hosted on a remote computer over a network. Remote Desktop Services sessions run in a single shared-server operating system and are accessed using the RDP Remote Desktop Protocol.