concrete5 184.108.40.206 is a maintenance release that fixes a number of bugs found in concrete5 5.6.0. It is highly recommended for users of concrete5 5.6.0.
220.127.116.11 builds on the impressive 5.6.0 update that adds a completely new permissions and workflow system to concrete5. Get more information about concrete5 5.6.0 here.
You can download concrete5 18.104.22.168 from the concrete5 downloads page: