The Difficulty mode is a character setting selected during character creation. There are 3 different options: Softcore, Mediumcore, and Hardcore. The difficulty mode of a character determines what happens upon their death. Once a character has been created, its difficulty cannot be changed.
There is also a choice between Normal and Expert mode when creating a new world. This is a separate setting that applies to the world, rather than the character, and similarly can't be changed once the world has begun generating.
Softcore is the default character mode, and the easiest.
Softcore characters drop half their coins on when killed by a boss or enemy (rounded up), which can be retrieved upon respawning, but may also be collected by other players in Multiplayer. Softcore characters respawn at their spawn point after death, following a short delay.
Characters in the 移动版 are automatically set to Softcore on creation.
In an Expert mode world, Softcore characters will drop 75% of their money, instead of the usual 50%. Enemies can also steal your coins and despawn, which can be a huge setback for the player.
Mediumcore characters drop all of their items upon death, including all coins and ammo. These can be retrieved upon respawning, but may also be collected by other players in Multiplayer, and by enemies in Expert Mode. Mediumcore characters still respawn at their spawn point after death, following a short delay.
Hardcore characters die permanently, and drop all of their items upon death, including coins and ammo, which other players can then collect in multiplayer.
Death causes a Hardcore character to become a Ghost that can continue to observe the world but not affect it. Ghosts can fly, pass through walls, and continue to chat with other multiplayer users, but cannot interact with the environment in any way and cannot open a map. Other players are not able to see Ghosts.
Once a dead Hardcore character quits the current world, that character is permanently deleted. Items the character placed in Chests will not be deleted, but items the character had in portable storage (Piggy Bank, Safe, Defender's Forge) will be deleted.