The Chat activity allows course participants to have a real-time synchronous discussion in a Moodle course. Different themes may be used (although note that you lose the conversation thread if you change mid-chat) and an accessible interface is available.
The Chat tool is a real-time, text-based collaboration tool. You can use the Chat tool to brainstorm ideas, hold a question and answer period, have a debate or discussion, or organise a remote study group. As opposed to other collaboration tools, such as Discussions, Chat conversations occur in real-time. In Brightspace you can have personal chats or general (course) chats.
This features works well in both platforms.