Glycogen and starch are both polysaccharides, which means they are made up of long chains of sugar molecules. However, there are some key differences between the two.

Structure: Glycogen is a branched polysaccharide, while starch is an unbranched polysaccharide. This means that glycogen has a more complex structure than starch.

Location: Glycogen is found in the liver and skeletal muscles of animals, while starch is found in plants.

Function: Glycogen is a storage form of glucose that can be quickly broken down to release energy. Starch is a storage form of glucose that is more slowly broken down than glycogen.

Digestion: Glycogen is digested by the enzyme glycogen phosphorylase, while starch is digested by the enzyme amylase.

Glycemic index: Glycogen has a higher glycemic index than starch, which means that it causes blood sugar levels to rise more quickly.

Overall, glycogen and starch are both important polysaccharides that play different roles in the body. Glycogen is a quick source of energy, while starch is a slower source of energy.