NM_Standalone: this instance of the game is without networking but still considered a server.
NM_DedicatedServer: this instance of the game is a server connecting all players with no local players.
NM_ListenServer: this instance of the game is a server connecting all players with a local player playing and is the host of the game.
NM_Client: this instance of the game is a client connected to a remote server.
ROLE_Authority: this instance of the actor has authoritative control (server).
ROLE_AutonomousProxy: this instance of the actor is a client that has some kind of autonomity (locally controlled by a human).
ROLE_SimulatedProxy: this instance of the actor is a client that is being simulated on other machines while being controlled by a human on a different machine.
An actor has 2 roles: local role and a remote role depending on where that actor is. For example if it's on the server side it would have a local Role of ROLE_Authority and a remote role of ROLE_AutonomousProxy || ROLE_SimulatedProxy.