What is the er doing that is different in each case? ?

What is the difference between the rough ER and the smooth ER? What is the ER doing that is different in each case?

Endoplasmic reticulum (ER) is a network of interconnected, flattened membranous sacs called the cisternae. It is of two types namely the rough Endoplasmic reticulum (RER) and the smooth Endoplasmic reticulum (SER). The surface of rough ER is characterized by the presence of the ribosomes whereas the surface of the smooth ER is smooth and do not show the presence of ribosomes.

The function of the rough ER and the smooth ER are different from each other. The rough ER is involved in the manufacture, packaging of proteins and synthesis of enzymes. The smooth ER is involved in the synthesis of lipids, steroid hormones and lipid metabolism.

thinking it would be physical characteristics

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.