Origins Reyvateil were the first ones to be created. They are directly connected to the towers upon which our world was built. We don't have gods, but I suppose they'd be the closest thing to them. There are three of them in total. Pureblooded beta types were created by cloning those three, although saying they're mere clones is not correct. As for Third Generation Reyvateils, they are the results of Pureblooded Reyvateils eventually mating with humans a long time ago.

The strongest difference lies in powers and abilities. A Reyvateil's magic power comes from a different set of factors, and one of those is the purity of the sound waves they are capable of emitting. In addition to that, third-generation Reyvateil don't have their own Hymn Code, and as such they cannot input commands in the tower of origin.