The orcs of Eberron are an incredibly diverse and deeply spiritual people. The oldest race on Khorvaire, the orcs are perhaps the only humanoid species on the continent that can truly claim to be native to it, and they were present on the continent long before any of the other races emerged. They are larger and stronger than humans, and are a deeply passionate people. Where the goblinoids tend to be lawful and rational, the orcs of Khorvaire are passionate and spiritual, they gravitate towards faith and were the first to practice druidic traditions on Eberron.
The orcs of the Shadow Marches have long been isolated from the rest of the world, and are split into several groups. Some of them exist in isolated tribes that shun contact with other races and cultures, and others gather in clans that welcomed the refugees from Sarlona over a thousand years ago. Many orcs view humans and the other races as respectable, but smaller, cousins.
Shadow March clan orcs see no taboo about cross-breeding between them and other species, and so half-orcs are common. The orcs refer to these children as Jhorgun'taal, which means "children of two bloods" in Orc and is seen as a mark of pride. Many of the orcs believe that the existence of half-orcs is proof that we are all one people, and they work hard to bridge the gap between the other races and the isolationist tribes.
Like all orcs, the orcs of the Shadow Marches are deeply spiritual, but they are not united under one religion. Some groups have fallen into cults of the Dragon Below, whilst others embrace nature and practice druidism. Notably, the Gatekeepers have a strong presence among some of the Marcher clans.
The orcs of the Eldeen Reaches were an offshoot of the Marcher clan orcs. They are among the most peaceful of all of the orcs, and work closely with the other druids in the forests. The faith of the Gatekeepers is strongest here.
There is also a sizeable population of orcs in the Demon Wastes. To survive in the demon wastes, it is not enough to be physically strong, but you must also be spiritual strong, and this is represented in the Ghaash'kala. These orcs see the demon wastes as a tainted land, and believe that any who enter it are forever stained. They see it as their sacred duty to prevent anyone who has entered the wastes from leaving. Despite this, they are often peaceful to those who come near the Wastes and are a proud and noble people. They are the enemies of the ancient fiends that populate the wastes, and are willing to accept those that are tainted by the land to join them against it, rather than die.
The Jhorash'tar are an alliance of orc tribes that dwell in the Mror Holds, and have done so since long before the arrival of the dwarves. Most of their tribes were annihilated by the dwarves, and they were pushed into the southwestern regions of the mountains where they clashed primarily with Clan Droranath and Clan Noldrun. They have their own distinct culture with nothing in common with the Ghaash'kala or the Gatekeepers, and have never formed large communities.