The structure of the two endoplasmic reticulum makes the difference.
Endoplasmic reticulum (ER) is located in the cytoplasm membrane in the eukaryotes and its divided into two the rough and smooth endoplasmic reticulum.
Rough ER has ribosomes which gives it the name rough because of its appearance. The ribosomes on rough ER helps it to specialize in the synthesis of proteins. proteins in a cell, are synthesize by it. The smooth endoplasmic reticulum lacks ribosome in its structure and cannot synthesize protein but lipids.
