Resources:
This is the folder for all resources which can be used to make maps. Think about tutorials, brushes, textures, map items, etc.
World:
This folder is meant for maps depicting an entire fictional world. The definition of 'world' can change of course, but generally this folder is meant for maps which show all of some world and not just parts. This folder is not meant for maps of our own Earth, they can be submitted to Real World.
Regional:
This folder is meant for maps depiction region of a fictional world, most maps fall into this category. Again, maps depicting a region of our own Earth can be submitted to Real World.
Tactical:
This folder is meant for all maps which have a tactical/game purpose. The main example are dungon maps, but also floor plans of castles and towns with a grid can be found in this folder.
Real World:
This folder is meant for all maps depicting a truthfull version of our own Earth, be it historical or of the present. They can either be of the entire world or just of regions. Remember that this group is meant for original maps, so a scan of an atlass will still not be accepted

Science Fiction:
This folder is meant for maps depicting a future world or region, this will include most space maps (except those which are a realistic version of the world as we now know it

Town & City Maps:
This folder is for all maps depicting fictional human settlements, so from villages to large cities.
Alternate Earth:
This folder is meant for maps of alternative versions of our own earth. In practice, these will mostly be alternate history maps, so if you have an alternate history map, this is the folder to submit to. Maps of any purely fictional region/world which are not meant to depict a place which was originally historically real can be submitted to Regional or World, not to this folder.
Miscellaneous:
This folder is for any map which doesn't fit any of the descriptions above. If you believe this to be the case, you can submit to this folder. Examples are a map of a Wyvern lair, a map of a ship and a map of a tide pool.