Hi,
If you add other accounts to the Messages app after activating the iMessages account then by default (if you don't name them in the Description box) that take the name of the Service they join up to the point you have a second AIM valid Name or a second Jabber valid Name.
In My List my accounts are Named in the Description Box
AIM is Aol Instant Messenger so the Add Screen Shows AOL. You will see in the right hand pane under Account Info it says it is AIM.
You will see in the list several others are also AIM Valid accounts.
If you don't Name them yourself then the account info is used (like the iMessages one) when you have two or more for that service.
Google and Facebook run Jabber servers.
They are unlikely to work with a Hotmail ID (which is MSN and not Native to the Messages app).
You seem to have Added an Account as Google and tried to use a Hotmail ID
As the Google Servers only allow IDs that end @Googlemail.com or @gmail.com it will not work and you will be "Off Line".
The ID is "accepted" when you type it in as it conforms to an email Address.
Japib has their Facebook account called chat.facebook.com which happens to be the server name and that it how it appears in the list on the left in their Pic. It will also be in the Window Menu like that.
See also an older iChat version when you could only login one account type of each
http://www.ralphjohns.co.uk/iChatPicsFolder/2%20iChat%20menus/slides/8_iChat_Men u_Window.html
There were only AIM and Jabber back then.
9:18 pm Tuesday; December 30, 2014
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Couple of iPhones and an iPad