Answer:
Photorespiration is defined as a respiratory process in many higher plants in which plants take up the oxygen in the presence of light and produces carbon dioxide while in photosynthesis plants utilises sunlight and carbon dioxide to produce oxygen.
C4 plants able to photosynthesize with no apparent photorespiration because they use Phosphoenolpyruvate (PEP) carboxylase in order to fix CO2.
CAM plants keep the stomata closed throughout the day, thus reducing water loss.
Thus, Both reduce photorespiration but during carbon fixation they use more ATP and able to photosynthesize with no apparent photorespiration.