child vs. parent partitions

[OfftheWall]

Is there any major difference between using a child partition vs. using a parent partition with Microsoft Virtual Server?

[suwunk]

The root partition is essentially a virtual machine which runs a copy of 64-bit Windows Server 2008 which, in turn, acts as a host for a number of special Hyper-V components. The root partition is responsible for providing the device drivers for the virtual machines running in the child partitions, managing the child partition lifecycles, power management and event logging. The root partition operating system also hosts the Virtualization Stack which is responsible for performing a wide range of virtualization functions (the Virtualization Stack and other root partition components will be covered in more detail later in this chapter).

Child partitions host the virtual machines in which the guest operating systems run. Hyper-V supports both Hyper-V Aware (also referred to as enlightened) and Hyper-V Unaware guest operating systems.
An Overview of the Hyper-V Architecture - Virtuatopia (http://www.virtuatopia.com/index.php/An_Overview_of_the_Hyper-V_Architecture#Hyper-V_Root_and_Child_Partitions)