Are you asking with respect to Hardware Configuration of a system ?
If yes, It is the server administrator who decides the hardware based on the load expected on the server.
There are commands to find out your hardware configuration and usage like
If you are asking with respect to Operating system,then I hope there no such command which differentiates between Server and Desktop Operating system. It it the vendor who targets the Operating system for Desktops/servers.
For example Ubuntu/Fedora are targeted for Desktops, CentOS/RHEL are targeted for servers.