More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is
more active nature of the actinoids
more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
greater metallic character of the lanthanoids than that of the corresponding actinoids.
