Fan Fiction Editors: a person who is responsible for curating fan fiction section/edit/modify fictions. They don't have moderation rights.
Coolbies: is a member who provides written updates for a show on a regular basis. They dont have moderation rights.
Viewbies/Vbies: looks after a forum. Promotes healthy discussion and activities and has moderation power to promote/close/open/edit/stick topics/issue warning pms and increase warning levels (only if a member violates IF COC)
Coolviewbie: is a member who provides written updates for a show on a regular basis and also has moderation rights same as a viewbie.
Moderators/Mods: a rank above a viewbie with more moderation power.
Channel Moderators/CMs: a moderator who handles forums under a particular channel.
Global Moderators/Greenies/GMs: a moderator who has moderation rights for the entire website.
Development team members is a team who work around IF to maintain peace of make sure other members follow the code of conduct of IF. They have certain rights to themselves which they will use if necessary. The DT heirchary includes
Channel Moderators - handle all forums under a particular channel.
Moderators - handle the respective forums they are assigned. They have slightly more power and authority than Viewbies.
Viewbies/Cool Viewbies - handle the forums they are assigned and ensure that healthy discussion is promoted in the forum and it remains conflict free.
Above them lie Global Moderators who have moderating rights over entire IF.
Coolbies are also part of the development team however they only provide updates to particular shows and do not have the same rights as moderators. They do not handle forum issues.
Credit : Angel-Jot, Ishan and MsChanadlerBong