Here's a breakdown:

* Cell walls are rigid structures that provide support and protection to cells.

* Lipids are fats and oils, which are primarily composed of fatty acids and glycerol.

The composition of cell walls varies depending on the organism:

* Plants: Primarily composed of cellulose, a complex carbohydrate.

* Bacteria: Made of peptidoglycan, a polymer of sugars and amino acids.

* Fungi: Composed of chitin, a complex carbohydrate similar to cellulose.

While lipids play important roles in cell membranes, they are not the primary building blocks of cell walls.