The West Kingdom utilizes a unified website system that employes a single large web application that hosts all of the content for multiple independent sites on a single code base, with a single database. Each individual site is served from its own URL, and has its own distinct appearance, which sharing a common user base and calendar with the Kingdom site.
The motivation behind using a unified system, rather than using independent websites for each group, is that this allows all of the effort that goes in to managing the content of the Kingdom calendar to be shared by all of the hosted sites. This avoids the problem where smaller groups' website calendar if their site administrator becomes too busy to make timely updates to the site.
The unified system is in the process of being rolled out, and has not yet been adopted by all branch groups.