What do the club roles mean?

Five steps, each including everything below it:

• Guest — in the club but not yet approved; read-only.
• Member — the normal role: post, comment, chat.
• Moderator — also handles reported posts and comments.
• Admin — also club settings, threads, members, banners and donations.
• Owner — the creator. Cannot be removed or banned, and is the only role that can promote or ban an admin.

Roles are per club: being an admin of one club gives you nothing in another.