| Light reaction | Dark reaction |
| 1. Occurs only in the presence of light. | 1. Occurs in the presence or absence of light. |
| 2. It is light dependent reaction. | 2. It is not dependent on light. |
| 3. It occurs in grana thylakoids of chloroplast. | 3. It occurs in stroma of chloroplast. |
| 4. The end products of the light reaction are ATP, O2 and NADPH. | 4. ATP and NADPH help in formation of glucose. |
| 5. H+ ions are formed. | 5. H+ ions formed in photolysis are picked up by NADP |
| 6. Light energy is utilised in splitting water molecule. | 6. CO2 is utilised and glucose in formed. |