Question:
Why when using Asianux Server 3 SP2 as the guest OS, when installing para-virtualization or full-virtualization, is the list of “base packages” different?
Answer:

In full-virtualization mode, the kernel-xen packages are on the list because the installed OS can boot regardless of which kernel is installed (normal kernel or xen kernel).

In para-virtualization mode, the kernel-xen packages are mandatory and, as such, are not on the list of packages to install.