It can be rather confusing what the differences and similarities are on Fedora, Red Hat Enterprise Linux and CentOS. Especially with different versions. This article explains what release schedule and relations the various RPM based Linux distributions have.
Fedora is a Red Hat sponsored community project. Fedora is release approximately every 6 month. Fedora "supports" (supplies updates) for 13 month only. Clearly this is a development distribution.
Red Hat picks up a Fedora version and adds a few patches and call that "Red Hat Enterprise Linux". Red Hat supports that version for quite some time. Red Hat releases more conservatively; every 2 years. Red Hat supports a release for about 5 years after releasing, making this distribution much more "enterprise".
|Fedora release||Red Hat release|
|Fedora Core 3||Red Hat Enterprise Linux 4|
|Fedora Core 6||Red Hat Enterprise Linux 5|
|Fedora Core 13||Red Hat Enterprise Linux 6|
CentOS picks up the source code that Red Hat published for Red Hat Enterprise Linux. The CentOS community patches the artwork and very few other things. CentOS "supports" (provides updates) for as long as Red Hat supplies updates to Red Hat Enterprise Linux.
Interesting to know; once you have choosen to use a certain main version of CentOS, you'll automatically update to the most recent child-version of that release when using "yum update". So; if you install "CentOS 5.0" and run "yum update", you will automatically have "CentOS 5.7". (at the time of this writing.)
So; this makes this image: