Let's start with the terms used in Zujo meeting Client SDK.
A Meeting represents real-time audio, video, and/or screen-share session, and is the basic building block for media sharing among participants. Supports upto 20 participants.
Participants are the client applications that are connected to a Meeting and shares audio and video media with one another.
Participant producing audio or video stream from the local client's media sources
Streams are indiviual audio and video streams produced by the participants in the meeting
Active speaker represents the participant who is currently producing highest decibels audio stream (in other words speaking)
Active presenter is the participant who is currently sharing his/her screen as a video stream
Main participant represents the client who shall be displayed on the main screen indicating that he/she is either presenting or speaking