Fedora is all newest/latest/greatest applications, and not as rigorously tested. Support, such as it is, for it will be dropped much earlier than for RHEL. There is no guarantee that Fedora can be 'upgraded' from version to version without a complete re-install. It is a kind of beta-like distro. The biggest upside is the newness of the included packages. Probably well suited for newbies. Command-line tools and such programs don't change much, if at all, so the two distros are pretty much identical in that respect.