There's a lot of different usages that may not heat the GPU as much. Also Windows might have better thermal management in the drivers. CPU wise, Intel defines

There's a lot of different usages that may not heat the GPU as much. Also Windows might have better thermal management in the drivers. CPU wise, Intel defines their TDP as the average heat dissipation, but the CPU can boost higher than this. But from what I understand they tell manufactures to design to the TDP.