LXD is a new thing from Canonical, a hypervisor designed especially for containers that is supposed to guarantee hardware isolation.
Nope, it currently defaults to libcontainer[1], not LXC, but through the use of execution drivers[2] you can still use LXC if you want to.
[1]: https://github.com/docker/libcontainer
[2]: http://blog.docker.com/2014/03/docker-0-9-introducing-execut...
LXD is a new thing from Canonical, a hypervisor designed especially for containers that is supposed to guarantee hardware isolation.