This is the only Sonaro I have seen.
It is possible the model name was re-used, but I don't know this.
Probably no real difference. Sunn used the same circuit in a number of heads with different model names.
As I said, Sunn in the early days named their amps based on a head/speaker combination. The same head internally would have a different name because the speakers were different.
As an example, the 100s and Sceptre were the same amp head, different speakers. The heads are only different because of the name on the front panel.