Forum OpenACS Q&A: OpenVZ
OpenVZ is an Operating System-level server virtualization solution, built on Linux. OpenVZ creates isolated, secure virtual private servers (VPSs) or virtual environments on a single physical server enabling better server utilization and ensuring that applications do not conflict. Each VPS performs and executes exactly like a stand-alone server; VPSs can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.
The one thing that a zone cannot do is run a different version of the OS - that is, each zone can only be a Solaris 10 instance.
However, OS patches, new packages, etc. can be installed once and made available to all instances immediately; and the disk space used is the space taken by the package, plus a few KBytes for each zones package database.
And yes, inittab works properly inside a Solaris zone, unlike the possibly strange behavior you will run into under a vserver.
Moreover, Virtuozzo/OpenVZ historically precedes vserver:
Virtuozzo/OpenVZ was started in 1999, first sources were made public in 2000 and the production version (1.0) was released in 2001. AFAIK, vserver project started only in 2001.
Vserver and OpenVZ code is very different.
The similarities exist only in the ideas and approaches, because they both provide virtualization. However, if the similarities have other reasons than the same task of these two projects, the ideas probably migrated in the opposite direction than what you imply, from OpenVZ to vserver. But I'm not certain if it really took place.