For total efficiency you multiply that by the electromechanical efficiency of the motor, which for small motors is small unless they go very very fast
It depends on the type. Brushless DC fan motors are smaller, lighter, quieter, cooler-running, more durable and up to 70% more efficient than conventional AC fans (say 15 watts instead of 50 watts for a fairly powerful fan). However, there are some losses in the ESC systems that control them, where used.