For its FE2 Variant, see "Crazy+ Maps" in the FE2 Wiki.
The Divine difficulty is the highest difficulty TRIA.os. The only divine maps in the game are TRIA: RESURGO, Electrical Malfunction, Aurelius, and Monoscape and Electron Memories. It is a difficulty that cannot be accessed by anyone but the TRIA team (if they think your map is worthy of the title).
The other difficulties are:
Divine's difficulty color is magenta, Extreme's color is orange, Insane is purple, Hard is red, Normal is yellow, and Easy is green. You may find them by going to the in-game console and looking at the colors. Or go to the search button above and click Search, and the chosen difficulty will search for map that is the difficulty as shown in the search.
There is a 'Valiant' difficulty that will be added in V 0.6 of the game that will be the same difficulty as Divine, but will be free for developers to use, unlike Divine, which is only chosen by members of the TRIA team, if your map is at the difficulty of a Valiant map and it has enjoyable gameplay, design, detail, etc.