The Great Houses in the Dune universe rule fiefdoms as bestowed by the Emperor (and their ancestral planets, generally). So, they are feudal lords but they also exercise near total authority on their worlds. House Corrino has a semi-checked (by the Lansraad and somewhat by CHOAM and the Spacing Guild) authority over everything in known space, but rarely exerts it directly so the leaders of the Great Houses effectuate complete control over their planets and the populaces of them.
The Great Houses in the Dune universe rule fiefdoms as bestowed by the Emperor (and their ancestral planets, generally). So, they are feudal lords but they also exercise near total authority on their worlds. House Corrino has a semi-checked (by the Lansraad and somewhat by CHOAM and the Spacing Guild) authority over everything in known space, but rarely exerts it directly so the leaders of the Great Houses effectuate complete control over their planets and the populaces of them.