RDP stands for Remote desktop protocol. But we refer it as a service which allows you to remotely login to Our Cloud Servers from anywhere in the world and work. It is much better and advanced than traditional VPNs.
In Shared RDP all the resources are shared among users (Except your files), but in Private all the resources ar reserved for you. You can consider it like this (Bus = Normal RDP, Car = Admin RDP)For more details Check.