I used to work with Fedora until F15 and later I saw there were three different flavors (workstation, server and atomic(?)). These versions are mutually exclusive? What are their differences and purpose?
The difference is in the packages that are installed.
Fedora Workstation installs a graphical X Windows environment (GNOME) and office suites.
Fedora Server installs no graphical environment (useless in a server) and provides installation of DNS, mailserver, webserver, etc.
Fedora Atomic is designed around Kubernetes and containers.
One note worthy difference is the Repos that are available. You cannot use RPM Fusion or EPEL with Fedora server. This limits what is available package wise