What is the difference between a group contributor, member, and moderator?

When it comes to groups, you can either be a group moderator, contributor, or member.

Moderators:
If you create a group that you set to moderated, you will automatically be a group moderator/owner. This means that all of the tracks that get submitted to your group will only be added to your group once they have been approved by yourself or any other group moderator)

Contributors:
Contributors are people who have approved sounds in a group.

Members:
Members are people who have joined the group.  

Read more about groups here!