Every participant in a meeting is assigned a role as a Presenter or Attendee. A participant's role controls what they can do while in a meeting.  

The Organiser is creator of the meeting and cannot be transferred to another participant.  

The Presenter and Attendee roles are assigned by the Organiser either before the meeting in Meeting Options from the invitation, or during the meeting in the Show participants tab in the options of each individual participant. 

To read more about roles and permissions and how to assign them see Quick Guide to Settings for Effective Meetings in Microsoft Teams: Teams Meeting options. 

Tabled list of permissions and user rights for the Organisers and Presenters versus Attendees