Summary. 1. Glycogen is made up of only one molecule while starch is made up of two. 2. While both are polymers of glucose, glycogen is produced by animals and is known as animal starch while starch is produced by plants. 3. Glycogen has a branched structure while starch has both chain and branched components.lucose or sugar can be acquired from starch. We get starch from both plants and animals. The organs of our bodies like the liver, stomach, and the muscles are naturally able to produce the animal starch glycogen but we get most of our sugar from the starch which is produced by plants such as potatoes, wheat, and rice.