RedHat is a company specialized in Linux operating systems and related services. They provide Fedora for the Linux community and RHEL (Red Hat Enterprise Linux) for commercial power-users. RHEL is a commercial product.
CentOS is an open source initiative to provide a very similar service as the RHEL product for free. RHEL and CentOS are very similar, but not the same - in part because RedHat also offers various kinds of maintenance support.
Last edited by Tinkster; 10-30-2010 at 03:12 PM.