Steam Lobby vs Session Vs Server terminology in official UE website

I’ve been reading through this document relating to Network coding and Steam Sessions etc (using OnlineSubsystemSteam) (full page here: Online Subsystem Steam | Unreal Engine 4.27 Documentation )

but I am very confused. I have an old project which actually has a Steam App ID etc and is all set up as a closed alpha working on Steam (I made this but some years ago and with a lot of help. For now I use it as a working example). But in this working example I omit ```
bInitServerOnClient=true and then proceed to still use CreateSession and Lobbies.

The docs above says “not necessary if you are using Lobbies”.

I rewrote a new game, and using the same App ID I have at Steam I am able to connect with Steam. However, it fails to CreateSession unless I have the bInitOnServer flag set as above. But this is where it gets weird… a) why does my other game work without that line in DefaultEngine.ini? b) Actually read the screenshot. It contradicts itself. It says Lobbies give user info before joining (such as num players, map etc). Then directly below it says Lobbies does NOT give this information.

Did someone writing that make a typo/confuse Sessions and Lobbies? And if so, what is the correct summary of the differences between lobbies, sessions and servers.

I understand “Servers” may mean dedicated servers, which I am not working with right now. The working example AND this new rewrite are going to be “listen servers” or “host + clients” p2p connections.

I hope some of this question makes sense, and look forward to hearing the details of the summary between this terminology in the context of the engine/network Steam gaming.

Thank you for any help.

There is a related topic for reference here:[https://eoshelp.epicgames.com/s/question/0D54z00006xDWEZCA4/what-is-the-difference-between-lobbies-and-sessions?language=en_US](What is the difference between Lobbies and Sessions?)
I did not attempt to compare the differences between the two in practice, but as a programmer, my personal conclusion is that logically speaking, Lobby is greater than Session, and Session is more specifically used for game connectivity