Question

How can you tell the difference between rough ER from smooth ER?

Answer 1

Rough ER is called rough because it has ribosomes attached to its surface. The double membranes of smooth and rough ER form sacs called cisternae. Protein molecules are synthesized and collected in the cisternal space/lumen. When enough proteins have been synthesized, they collect and are pinched off in vesicles.

Answer 2

Both the smooth and rough endoplasmic reticulum help in the production and storage of proteins The main difference is that one contains ribosomes on it and the other does not. The rough endoplasmic reticulum has ribosomes on its surface. This is what give the RER a "rough" appearance.