User preferences; skins, items, terrain, etc: Settings for skins items and terrain are built in no modifying the jar. In the options menu you will be able to select themes or just certain pictures (char.png, terrain.png, items.png, etc). Each map can be customized differently and each map character can look different, if no custom theme is selected it use the default.


Server theme: items, terrain, etc. A multiplayer server can have a custom look (items, terrain, etc) when someone connects to the multiplayer server a user can select a theme they have on there computer or use the custom server theme.