You can say Fedora is the community supported version like Debian is. The updates will be constantly updated on its site and will be downloadable. On the othere hand, RHEL will not be sold in retail and will be the pure commercial way. While the various software/utilities will be tested by the community at large in the Fedora project, the tested ones will be finally included in the RHEL. Needless to add, RedHat will discontinue support for anything except RHEL in times to come.