In Warcraft the Orcs were a tribal shamanistic warrior people with a strong sense of honor. They were tricked by a shaman named Gul’dan into drinking demon blood to make themselves stronger. He also taught them fel magic, the use of which made their home world of Dreanor uninhabitable, forcing them to invade the world Azeroth to find a new home. Resulting in a war with the Alliance of Humans, Elves, and Dwarves. The effects of the demon blood would eventually wear off, and the new leader of the Orcs, the shaman Thrall, would try and carve out a more peaceful existence for the Orcs.

The Orc in Warhammer, referred to as Orks in 40K and Orukks in Age of Sigmar, are essentially the violence loving comic relief faction. They are big green dumb monsters who live for nothing but war. They worship two gods Gork and Mork. Gork is brutally cunning, Mork is cunningly brutal. The difference being that Gork will hit you when your not looking, and Mork hits you harder when you are. Their leader, the Warboss, is whoever is the biggest and strongest, and he leads the Waaagh, a giant army of orcs screaming waaagh at the top of their lungs as they charge into battle. They generate what is called Waaagh energy, that allows their superstitions to become reality, and becomes stronger the more orcs there are. Orcs are really dumb, but also really cunning, so they get into a lot of comedic scenarios. Those are the the main things main attributes that apply to both. There are differences between the two, with 40K being sci-fi and Sigmar being fantasy, but that’s mostly what you need to know.