Difference between Chat Permission & Chat with Authorized People

[ok-n@community.nodebb.org]

I see in my forum’s admin panel, under permissions, there are 2 columns, 1. Chat permission. 2. Chat with authorized users.
What is the difference between them, and who are the authorized users and how do you make a user or group authorized in this respect?
(By the way, my goal is to allow chat only with a group of administrators and not with a regular user with each other but only with the administrators)
Thanks!