Administrators or Admins are people who are responsible for running the community. Monitoring control over the entire community is the foundation of their responsibilities. Of course this implies various things such as setting and modifying rules, making sure conversations are relevant and moderated, assign jobs or roles to members, create and observe channels (see Channel), among many other things.
Admins are also responsible for making announcements, organising and coordinating events, sharing resources, responding to concerns and tending to them, and in general have entire control over how the community functions as a whole.
The long-term goal of administrators is to help build a thriving community of people and foster healthy relationships and discussions.
Channels are spaces within communities that help further streamline discussions and increase the relevancy of conversations. Usually, when you first join a community, you will be greeted with a guide to what each channel is for, and depending on what question, interests, or resources you might have, you can pick out the relevant channel and strike a discussion there.
Community facilitators or facilitators in a community are those members of the community who help you run it. They can be officially appointed or indirectly be so heavily involved with the community that they can be considered Superusers or Superfans on the verge of becoming administrators.