what is the difference between Redhat Linux and Redhat Enterprise Linux. whereas Redhat linux have Server installation options too.
The last release of Red Hat Linux, i.e. 9, was in 2003. Red Hat Enterprise Linux continues to be developed and released.
Red Hat Enterprise is a commercial Linux product which continues to be updated and supported to this day.
Red Hat was the noncommercial, non-enterprise version of it, which Red Hat Inc. stopped offering in 2003. The public community took up the slack and Fedora is the modern equivalent. I'm not sure how far the two have diverged by now.