The OpenELEC makers usually follow the XMBC releases, but it's been a while since the last XBMC version. This doesn't mean that the devs will stay put and wait for changes to come from upstream. In fact, OpenELEC is a distro and there are other components that need to be updated and fixed, as necessary.
“This release includes some bugfixes, security fixes and improvements since& OpenELEC-4.0.5 . Besides the usual bugfixes and package updates we fixed boot issues on some AMD mainboards, added support for some more Intel, AR3k and ATH6k Bluetooth and WLAN devices, updated Kernel to 3.14.8 and updated the RaspberryPi firmware to include the last fixes and features. OpenELEC-4.0.6 is now the next stable release, which is a bugfix and securityfix release of the OpenELEC-4.0 series,” said the developers on the official website.