An  OS  template  is  basically  a  set  of  packages  from some Linux
   distribution  used  to  populate  a  container. With OpenVZ, different
   distributions  can  co-exist  on the same hardware box, so multiple OS
   templates are available.

   An  OS template cache is an OS template installed into a container and
   then  packed  into  a  gzipped  tarball.  Using  such  a  cache, a new
   container can be created in a matter of minutes, if not seconds.

   For  information  about  templates  and installation instructions, see
   [1]wiki:OS template cache preparation.

   Utilities
          Template utilities is a software aimed at template maintenance,
          such  as  creation  and  update  of  templates  and  continers.
          Currently  these  consists of vzpkg, vzyum and several versions
          of RPM utility repackaged for OpenVZ.

   Metadata
          Template  metadata is data needed to (re)create template cache.
          Metadata  for  a  template  contains the following information:
          list  of packages that form this template; locations of package
          repositories;  scripts  needed to be executed on various stages
          of  template  installation;  public  GPG key(s) needed to check
          signatures of packages; additional OpenVZ-specific packages.

   Precreated
          An  OS  template  cache  is  an  OS  template  installed into a
          container  and then packed into a gzipped tarball. Using such a
          cache,  a  new container can be created in a matter of minutes,
          if not seconds.

References

   1. http://wiki.openvz.org/OS_template_cache_preparation