In general, a leveled list allows the choice of object or actor to be dependent on the level of the player relative to the Encounter Zone. Therefore as the player grows in level, the actor or object generated changes. Loot in containers is better. Creatures and NPCs encountered are tougher.
GECK v1.1 Bug:When using a leveled list as template, make sure you have a creature/NPC of level 1 in the list. Otherwise the game will crash.
This issue may be fixed in future releases of the GECK.