OpenVZ is a OS-level virtualization software that allows you to run isolated, secured containers that use a modified version of the Linux kernel to split the physical server to allow you to run multiple isolated containers, sometimes also called virtual private servers, that act as their own independent servers and have their own properties that are:
Root account
Users
Filesystem and quotas
Processes
Memory limits
CPU quotas
Network configuration
Each of the containers shares the same hardware and resources from a single physical server called a node.
The operating systems on the server cannot be mixed; they must run the same operating system as the physical server. Since you are using Linux for OpenVZ, you can only install Linux containers, although you can use different distributions of Linux for each of your containers.