- Fedora does its thing informed by but somewhat independently of RHEL.
- Red Hat chooses a Fedora release to be the base of RHEL, forks it, and starts working on it.
- This eventually becomes RHEL X.
- Red Hat then forks RHEL X to create the RHEL X.0 Beta and eventually the RHEL X.0 release. RHEL X keeps getting work done on it which eventually lead to another fork which creates RHEL X.1 Beta and RHEL X.1.
- After each RHEL X.y is released CentOS starts the process of rebuilding it from the sources and tracking upstream changes.
The new model puts CentOS where RHEL X is and so RHEL X.y are actually forks of CentOS.
This change matters a lot to you if you care a lot about the difference between the minor releases of RHEL because there won't be CentOS 7.1 CentOS 7.3 but just CentOS 7. If you just yum update on CentOS then you probably don't care since by default it will move you up minor versions. You have to try to stay on a specific minor version.
What's nice about this change is that anyone can peel off releases from CentOS the same way Red Hat will do to make RHEL and new features become available when they're ready instead of being batched.