In terms of functionality and purpose, how does Nano compare to Server Core?

Nano server is the operating system which optimize for the data center and the private cloud.

It is the new version of window server that are basically developed by the Microsoft company for running various types of cloud applications. It basically support various types of tools and 64 bit application in the server.

Server core is the type of window server OS (operating system) and it only include the those types of components that is require to perform various types of applications and server role in the system. It does not contain GUI (graphical unit interface).