CBSE - Biology - The Fundamental Unit of Life

The ribosomes, which are present in all active cells, are the sites of protein synthesis. Endoplasmic reticulum helps in transporting these proteins to various places. The smooth endoplasmic reticulum help in manufacture of fat and lipids which along with proteins help in building the cell membrane.

Smooth endoplasmic reticulum	Rough endoplasmic reticulum
Ribosomes - Absent	Ribosomes - Present and is also called α cytomembrane
Position - Mainly present near the cell membrane.	Position - Mainly present near the nucleus
Occurrence - Mainly found in lipid forming cells e;g., adipocytes (Fat cells), interstitial cells (of testis), adrenal cortical cells, glycogen storing cells of liver, muscle cells, leucocytes etc.	Occurrence - Mainly found in protein forming cells e;g., pancreatic acinal cells, globlet cells, plasma cells(produce antibodies), Nissl’s granules of nerve cells etc.
Origin - Formed from RER by loss of ribosomes.	Origin - Formed from nuclear membranes.
Component - Mainly formed of tubules.	Component - Mainly formed of cisternae