A moderator is the person who owns the conferencing account, organizes the meetings, invites participants, and hosts, manages, and controls the meetings. 

If you create the account, you are the moderator and should always use the Moderator PIN Code when entering the audio and web conference.

A participant is a person who is invited to a conference. The participant dials into the audio conference and logs into the web conference as a guest and uses the the Participant PIN Code to enter the meetings.

Participants cannot control the meeting.