There are two types of endoplasmic reticulum: smooth endoplasmic reticulum and rough endoplasmic reticulum. The smooth endoplasmic reticulum is so termed because it does not have a ribosome on its surface. As a result, it has a more refined appearance than the raw ER. It has a role in the production of lipids (such as phospholipids) and carbohydrates, both of which are utilized to construct the cell membrane. Rough endoplasmic reticulum has ribosomes adhering to its surface, unlike smooth ER. It's involved in the cell's production of numerous proteins. The rough ER, on the other hand, is involved in the synthesis of antibodies, insulin, and protein trafficking into the smooth ER.