Starch consists of two components − amylose and amylopectin. Amylose is a long linear
chain of −D−(+)−glucose units joined by C1−C4 glycosidic linkage

Amylopectin is a branched-chain polymer of X -D-glucose units, in which the chain is
formed by C1−C4 glycosidic linkage and the branching occurs by C1−C6 glycosidic linkage.

On the other hand, cellulose is a straight-chain polysaccharide of β-D-glucose units joined by C1−C4 glycosidic linkage (β-link).
