Back in the days when Solaris 10 was released, there was a big stir about ZFS and DTrace. Some people said that those are not that interesting, but Containers were the big thing. Containers were a new type of virtualization, a light weight virtualization where you only used one kernel. Solaris Containers used 40MB RAM and 100MB disk space for each new container. The Linux camp never got ZFS nor DTrace nor Containers. Later, BTRFS was created as a ZFS wannabe. And Systemtap as a DTrace wannabe. While Solaris people were talking about the big benefits about Containers, they were ignored by the Linux camp (Linus Torvalds said he never believed in virtualization and it was not a priority in Linux). Now, finally, the Linux camp also has realised that light weight virtualization is something wickedly cool. A couple of years late to the party, they tout lightweight virtualization as the greatest thing since sliced bread.
But still Linux camp has not grokked Solaris Containers. Solaris containers were reworked many times, and work started 2001 (or was it 1999?). It was called BrandZ and rewritten again under a new name, etc etc etc. After a couple of iterations Solaris Containers were released 2004. The difference to Linux version is that you can install other OSes in Solaris Containers, such as Linux. All Linux API calls are mapped to Solaris API calls. You could create a FreeBSD container as well, the code stubs are there. IBM has also copied Solaris Containers and call it WPAR. BTW, I think Bill Joy was involved in CHROOT back in the 1980s (one of the founders of Sun Microsystems and Solaris).