How do fungal cell walls differ chemically from plant cell walls?

The primary chemical difference between plant and fungal cell walls lies in their structural components. While plant cell walls are characterized by the presence of cellulose—a complex polysaccharide consisting of glucose units—fungal cell walls generally lack cellulose entirely.123

Instead, the main structural components of most fungal cell walls are chitin and various glucans. These fungal walls often feature an $\alpha$-glucan layer and a special $\beta$-1,3-1,6-glucan layer. In contrast, plant cell walls are typically composed of a mixture of cellulose, pentose-containing polysaccharides, and lignin, an inert, plastic-like material that provides rigidity.45

While some funguslike organisms may contain significant quantities of cellulose, the vast majority of fungi rely on the chitin-glucan matrix to provide structural integrity and protection.4