These are the four kits:
Starter Kit- contains iron gear and torches, arrows and basic needs for a starter on the server
Builder Kit- Contains materials for building a nice looking shelter, with stone brick, glowstone, nether quartz and other materials
PvP Kit - Chain armor and horse for a fun pvp match with friends
Decoration Kit- Used to decorate a players house with crafting tables, dye, plants and the likes.