Linux system components
linux version hairstyle
RedHat
RedHat Red Hat
Red Hat linux 9.0 after start charging for some services, but still remain free, free download.
Called Red Hat Enterprise Linux === RHEL 6.9 after charges.
Centos
Red Hat and CentOS do exactly the same
1. Remove the billing software in Red Hat
2. Remove the inside logo Hat
Fedora
Fedora is equivalent to the test environment, the new things to Fedora, the stable after it is transplanted to RedHat, then after a RedHat version, it is a version of Centos.