Necromancy is a school of magic whose spells manipulate the power of death, unlife, and the life force. A wizard who specializes in the necromantic school was called a necromancer. In the Fifth Dogma, some clerics undergo magical wizard in necromancy to become Mortalitasi.
FleshcraftDeals with the raising of undead with most of their soft tissues intact, and most notoriously the merging of several corpses into fleshy amalgamations.
BonecraftDeals with the raising of undead with little to none of their soft tissues intact. There are no stiff muscles, rotting gangrenous organs, or movement inhibiting ligaments, so control is much more easy to maintain and orders are more likely to be met with literal compliance. Bonecrafters can quickly and effortless raise small regiments of skeletal soldiers, given enough bones.
SoulcraftDeals with the living essence and soul of a mortal, rather than raising the dead per se. Soulcrafters are indeed able to create spectres and ghosts, but they are more concerned with either harming or healing.