A key difference between aerobic cellular respiration and the light reactions of photosynthesis is (are):

The light reactions of photosynthesis generate ATP, but aerobic cellular respiration consumes ATP.

In aerobic cellular respiration, ATP is produced through chemiosmosis, but in photosynthesis, ATP is produced through substrate level phosphorylation

Aerobic cellular respiration consumes reduced electron carriers (ex: NADH) to make ATP, but the light reactions synthesize reduced electron carriers (ex: NADPH) while also synthesizing ATP.

The electron transport chain of aerobic cellular respiration ends with the reduction of NAD⁺, while the electron transport chain of the light reactions starts with the reduction of NADP⁺.