Fedora 21 Workstation The Fedora Workstation is a new take on desktop development from the Fedora community. Our goal is to pick the best components, and integrate and polish them. This work results in a more polished and targeted system than you’ve previously seen from the Fedora desktop. We want our desktop operating system to solve your problems, not be your problem.
Fedora 21 Workstation features all of the latest GNOME 3.14 software, is powered by the Linux 3.17 kernel, and has a ton of other improvements and changes.
Fedora 21 Server The Fedora Server flavor is a common base platform that is meant to run featured application stacks, which are produced, tested, and distributed by the Server Working Group. Want to use Fedora as a Web server, file server, database server, or platform for an Infrastructure-as-a-Service? Fedora 21 Server is for you.
Fedora 21 Cloud : The Fedora Cloud Working Group and Special Interest Group (SIG) has been busy leading up to Fedora 21. Cloud is now a top-level deliverable for Fedora 21, and includes images for use in private cloud environments like OpenStack, as well as AMIs for use on Amazon, and a new “Atomic” image streamlined for running Docker containers.
For more detail about this release read Fedora 21 announcement