Incorrect, docker is built ontop of Linux kernel namespaces and cgroups. The first backend was LXC (notice the C and not D). The current backend is libcontainer, which is a native golang re-implementation (more or less) of LXC. There is a docker backend for LXC, but it is not the default and is likely not used super heavily.
Note that there isn't really a Linux kernel feature called LXC. The LXC userspace just ties all of the namespacing and cgroup functionality into 1 coherent super-chroot style environment. That is the same as docker does with libcontainer.
Is there a point-by-point (and detailed) comparison somewhere between FreeBSD jail and LXC (or libcontainer) ... it would be very helpful to see that comparison.
This is actually a pretty reasonable comparison. It is somewhat obvious the guy knows more about BSD Jails and elaborates a bit more on it, but overall, this is pretty accurate:
I just asked that on Twitter, because I also am not getting it. It seems to me that ZFS and Jails provide identical functionality, but without Docker's networking headache.
That said, even if my simplistic synopsis is correct, brining a Jails-like experience to Linux would still be a really solid step forward. Besides which, Jails have been underutilized at shops I've worked at. If Docker popularized the concept, that's still a huge win.
Note that there isn't really a Linux kernel feature called LXC. The LXC userspace just ties all of the namespacing and cgroup functionality into 1 coherent super-chroot style environment. That is the same as docker does with libcontainer.
http://www.infoq.com/news/2014/03/docker_0_9