Red Hat has split its Linux development into two lines
• Red Hat Enterprise Linux: Red Hat Enterprise Linux is officially supported by Red Hat. It is a commercial version and if you are running important machines in production and if you require critical support from RedHat, RedHat Enterprise Linux is the best option. It also has many nice features that are useful if you are running more than a few servers. You have to pay the licensing fee to RedHat for using Redhat Enterprise Linux. You can download a trial Version of RedHat enterprise edition (for 30 days) from RedHat website, http://www.redhat.com. RedHat Enterprise Linux are normally released once in two years.
If you require stable, supported, and certified Linux (which is required if you are running a business, any critical application, government) then you should select RedHat Enterprise Linux.
According to RedHat, the benifits of RedHat Enterprise Linux are "Stable, reliable, and broadly supported. Easy to deploy and manage. Many certified applications and hardware systems available. Industry-leading combination of server performance/scalability and desktop features".
You can install RHEL 6 on systems with a wide variety of CPUs. RedHat supports six different CPU architectures:
o Intel EM64T
o Athlon/AMD64 (x86_64)
o Itanium (IA64)
o IBM zSeries
o IBM iSeries
o IBM pSeries
• The Fedora Project: Fedora is much more cutting-edge than RHEL is, and Fedora has a larger community of users willing to help out and give free support. Fedora is distributed for free and can be downloaded from http://fedoraproject.org/.
According to RedHat, the Fedora Linux OS is for "developers and high-tech enthusiasts using Linux in non-critical computing environments".
Normally a new Fedora Core will be released in every six months.
Please visit the RedHat link to find more difference between RedHat Enterprise Linux Operating System and Fedora Operating System.