Definitely more powerful, but Otto's position is more precarious than his brother's. His brother's position (which is still considerably powerful) is far more cemented and he certainly knows that. Anyway, as mentioned, Otto is going to listen to his older brother who heads his family's ancestral seat.
So I don't yet buy any theory that Otto is being controlled by his brother. It seems they are two brothers with broadly the same ambitions for their House, and Otto's brother just reminded him to wake up and remember to use his influence toward the shared goal.