Realms are the individual factions servers.
There are 8 realms on SaiCo, each with different experiences. They all are the same except with different plugins added.
Skeleton Realm Edit
"Nothing more than Endless Piles of Bones, or so you may think... Beware..."
The Skeleton Realm is a generic faction server, with, of course, the Headhunting plugin added to all realms.
Zombie Realm Edit
"A Demonic Plague has ravaged this realm, do you Dare to hunt in this Deadly Place?"
The Zombie Realm is the same as the Skeleton Realm, except with the added bonus of mcMMO Skills.
Wither Realm Edit
"A Desolate Wasteland full of Corruption due to its New Inhabitants..."
The Wither Realm has the added twist of OP Enchantments.
Witch Realm Edit
"Cast into Eternal Darkness by the Necromancers that inhabit the realm.."
The Witch Realm has Custom Enchantments made by SaiCoPvP.
Ender Realm Edit
"A Utopian Realm which was devastated by its Essences being used to bring destruction..."
The Ender Realm has the same experiences of the Witch Realm.
Blaze Realm Edit
"The Gates Of Nether have been unleashed Infesting this Hellish Realm with many demons..."
The Blaze Realm has the same experiences of the Skeleton Realm.
Magma Realm Edit
"Endless lakes of lava with many fierce Abominations lurking beneath its depths..."
The Magma Realm has the same experiences of the Zombie Realm.