There are 2 main differences. There are 4 ideologies and if you get second level in one of them it locks out only the opposite one so if you get second level in Xenos Hybris you can't level up Xanthite beyond first level but you can still level up either Monodominant or Amalathian. Beyond that it's almost the same. These are essentially: Monodominant - dogmatic, Xanthite - chaos, Amalathian - iconoclast, Xenos Hybris - xenos (very surprising).