Similarities ..
→ Both involve in production of energy
→ Both involve the exchange of gases
→ Both the process takes place in cell organelle which was considered as endosymbiotic organism. They are chloroplast and Mitochondria, Photosynthesis takes place in Chloroplast where as respiration takes place in mitochondria.
→ At critical condition both have alternate pathway.
Differences...
→Photosynthesis takes place in chloroplast, where as respiration takes place in mitochondria.
→Photosynthesis involve production of carbohydrate and respiration involve breaking of carbohydrate.
→ Photosynthesis occur only during presence of sunlight where as respiration occurs all the time.
→ In photosynthesis process Oxygen is released where as in respiration Oxygen is utilised.
These are the main differences between Photosynthesis and respiration.