| S.N. | RER (Rough ER) | SER (Smooth ER) |
| 1. | It is composed mainly of cisternae. | It is composed mainly of tubules and vesicles. |
| 2. | It bears ribosomes on its cytoplasmic surface. | It is free of ribosomes. |
| 3. | It usually lies deep in the cytoplasm. | It usually lies near the cell membrane. |
| 4. | It takes part in protein synthesis. | It takes part in the synthesis of lipids, steroids, glycogen etc. |
| 5. | It arises by the outfolding of nuclear envelope. | It arises from the RER after the detachment of ribosomes. |
| 6. | It gives rise to SER. | It gives rise to Golgi apparatus, lysosomes and vacuoles. |
| 7. | It contains ribophorins to bind ribosomes. | It lacks ribophorins. |
| 8. | It has pores to let polypeptides synthesized on ribosomes to pass into the lumen of endoplasmic reticulum. | It lacks pores. The materials synthesized on SER are released into the cytoplasmic matrix. |