What is the difference between physical digestion and chemical digestion?

You can relate physical changes to the nature of chemical changes. Physical change is a kind of mechanical action, which only changes the shape and size of matter, but does not change the essence of matter.

For example,

You chew food, but the food particles become smaller, which is physical digestion, and the other is the mechanical stomach in the stomach.

Chemical digestion is to change the properties of substances,

The salivary amylase secreted by your mouth changes the properties of starch, which is hydrolyzed into maltose or glucose, which changes the properties.

In addition, food will be degraded in your gastric juice, such as the hydrolysis of lipids (fat) and the hydrolysis of some protein under the action of gastric acid.

In addition, after chyme enters the small intestine, the enzymes in pancreatic juice secreted by the pancreas will hydrolyze chyme relatively thoroughly (protein, sugar and fat are all converted into basic units).

Because of the mechanical action of food in the mouth and stomach, this food is mushy, just like cooked porridge, so it is called chyme. These are all chemical digestions.