differences between openvz and virtuozzo

openvz doesn't have vzfs, for one

Virtuozzo File System (VZFS) :

VZFS is a file system that allows to share common files among multiple VPSs without sacrificing flexibility. It is possible for VPS users to modify, update, replace, and delete shared files. When a user modifies a shared file, VZFS creates a private copy of the file transparently for the user. Thus, the modifications do not affect the other users of the file. Main benefits of VZFS are the following:

- It saves memory required for executables and libraries. A typical VPS running a simple web site might consume around 20–30 MBytes of RAM just for executable images. Sharing this memory improves scalability and total system performance;

- It saves disk space. A typical Linux server installation occupies several hundred MBytes of disk space. Sharing the files allows you to save up to 90% of disk space;

- VZFS does not require having different physical partitions for different VPSs or creating a special “file system in a file” setup for a VPS. This significantly simplifies disk administration;

- Disk quota enables the administrator to limit disk resources available to a VPS on-the-fly, in the same manner as the standard disk quota system works on a per-user basis. Disk quota for users and groups inside VPSs is also supported.