[Koha] Stable vs maintenance releases?

Can someone explain the difference between these two? http://download.koha-community.org/ lists these as 3.8.3 (stable) and 3.6.7 (maintenance) ... I would have thought that a maintenance release is done "on top of" a stable release, comprising minor bug fixes and the like. And how is it determined what the latest "stable" release is? I notice that Equinox's support page is still listing 3.4.1 as the current stable version. Is this something that varies from support company to support company, depending on their confidence in a particular release, their philosophy of development, etc? With thanks, Cab Vinton, Director Sanbornton Public Library Sanbornton, NH Life is short. Read fast!