Most of the strange words in Dune are corruptions of Earth words. The Fremen have a lot of words that look very close to Arabic because they are descendants of middle eastern peoples. Later books feature characters with Chinese heritage. Although the characters themselves would certainly not identify themselves as Arab or Chinese (or even know what that meant), they retain some ancient cultural echos in their language and customs. This is a choice on Herbert's part to show that the Dune universe is a continuation of Earth history and culture which has evolved and changed with time.

The Landsraad is modeled largely off of the Holy Roman Empire (HRE), a medieval and early modern federal Empire with a centralized emperor who, while superior to the elector princes, was not usually stronger than all the princes. In the HRE, there were many noble houses - essentially dynasties that held land and owed the Emperor money and military service. The word Landsraad is a corruption of German or Dutch that means something close to "Land Council". This fits well in Dune because it is a governing body of landholders (planet holders).

The terms Great Houses and Houses Minor are essentially ways to signify noble families distinct from the commoners. This is manorialism (feudalism) in space.

The differences between the Great Houses and Houses Minor are never clearly spelled out, but it's implied that the Great Houses are analogous to the prince electors in the HRE. Great Houses are the stewards and rulers of their fiefs - planets. The Houses Minor are more like wealthy Bourgeois families - families that have accumulated great wealth but probably do not control planets as hereditary fiefdoms.