Redhat Enterprise Linux (RHEL)

Red Hat Enterprise Linux (RHEL) is another distribution of the Red Hat family. Based on Fedora by selecting the most stable packages, RHEL is mainly designed for professional users. RHEL releases are provided approximately every 18 mounths and supported by Red Hat and its partners for seven years. The RHEL family is comprised of four products, two designed for server sytems and two designed for client systems :

Red Hat Enterprise Linux AS ("Advanced Server") is designed for large departmental and datacenter server deployments, best suited for systems with more than 2 CPUs or more than 16 GB of main memory.
 * Red Hat Enterprise Linux AS

Red Hat Enterprise Linux ES ("Entry/mid Server") provides an entrylevel and midrange server operating system for the Intel x86, EM64T, Itanium2, and AMD64 markets. It's differentiated from Red Hat Enterprise Linux AS by its support for smaller systems and lower price.
 * Red Hat Enterprise Linux ES

Red Hat Enterprise Linux WS ("WorkStation") is ideal for "power user", software development, and technical applications such as virtualization/rendering. It includes a full suite of desktop productivity applications for tasks such as document creation, email, instant messaging, and web browsing.
 * Red Hat Enterprise Linux WS

Red Hat Desktop supports 32bit Intel x86 and 64bit Intel EM64T and AMD64 systems with one CPU and up to 4 GB of main memory. It provides the same software functionality as Red Hat Enterprise Linux WS but for smaller systems and at a lower price point.
 * Red Hat Desktop