How do clients Use 'NetworkServer.Spawn ();'?

I want the client to create the object

But ‘NetworkServer.Spawn ();’ it seems only server role

How do I make the client to create was built as a server?

Ideally, the server should create the object, then all the other clients will know about it too. The client player could use a Command to tell the server to do this.

    [Client] // called only on client
    public void SpawnObject(Vector3 location)

    [Command] // runs only on server
    private void CmdSpawn(Vector3 location)
        var obj = (GameObject)Instantiate(MyPrefab, location, someRotation);

This assumes that you have NetworkIdentity on your prefab, and that the Player object this is in is a NetworkBehaviour.

If I use a command and inside I call a RpcClient function to instantiate an onbject.
I am using only the Instantiate method and it is working, so why use NetworkServer.Spawn?
Dont got when i have to use it. What is the difference?