Q. What are the difference between plasma membrane and cell wall?

Plasma membrane and cell wall is not the same thing. Plasma membrane, also known as cell membrane, is the external membrane common to all living cells and it is made of embedded proteins, phospholipid bilayer and some appended carbohydrates.

Because cell membranes are fragile, in some kinds of cells there are even outer structures that support and defend the membrane, like the cellulose wall of plant cells and the chitin wall of some fungi cells. Most bacteria also present an external cell wall made of peptidoglycans and other organic substances.