Lobbymanager: Difference between "Lobby Player Prefab", "Game Player Prefab" and "Player Prefab"

I want to use the “Lobbymanager”
There are 3 Slots for Prefabs and I am not sure to which Moment theses prefabs get spawned and what the specific differences between this prefabs?

I’m assuming you are referencing the Unity Asset LobbyManager system, (Found Here):

Lobby Player Prefab:
This Prefab is automatically created for each player when the ‘Lobby Scene’ is loaded. In the LobbyManager Asset this corresponds to the UI Panel with the Player Name & Colour. It is created as soon as a player either joins or creates a game using the Matchmaker or the Manual connection.

Game Player Prefab:
This Prefab is automatically created for each player when the ‘Play Scene’ is loaded. In the LobbyManager Asset this corresponds to the players paddle. It is created once all players have clicked Join in the Lobby Scene, and the Game Scene has been loaded.

Player Prefab:
This Prefab slot doesn’t appear to be required as part of the LobbyManager. I’ve had it both populated and empty, and haven’t found a difference yet. You should be able to ignore it, or leave populate it with the same Prefab as the Game Player Prefab.