The type of icons differ depending on the server you are on,  the attached document lists and describes the different icons that is display in the member pane on the different servers.

Note:

As you are looking at the document there are some things to keep in mind.

• A Not Available (N/A) user is a user that is away from their computer for a specific amount of time (This time can be set in the Privia User Options)
• You can change the icon view in the membership pane to display smaller icons.