The same HSD concept but a little different. Camry HSD gas engine and electric motor spin faster and then it multiplies the torque with a speed reduction unit. Prius doesn't have SRU but relies on much higher torque in the electric motor. Prius' MG2 is 295 lbs-ft but Camry HSD's MG2 is rated 199 lbs-ft. Highlander Hybrid's gas engine is not Atkinson cycle but the Camry Hybrid use Atkinson cycle.