Fedora and its editions

No, CentOS has never supported upgrading from one major release to another. Period. While RHEL has such a feature, the software for that never got picked up by CentOS. They simply were not interested in it and no one stepped up to even make an attempt. While there are several recipes on various third-party HOWTO sites, they (often) led to completely broken systems and people looking for help in the #centos Freenode IRC channel... only to discover they will be resorting to backup.

Minor version upgrades however were like butter.