1. Subject classification: Red beans are leguminous plants, and red beans are seeds of leguminous herbs.
2. Shape and appearance: the shape of rainbow beans is long cylindrical, and the color is turquoise or purple-black. Red beans are round or nearly cylindrical, bright red, orange yellow or brownish red.
3. Nutritional value: Hongdu is rich in vitamins and minerals, which can clear away heat and toxic materials, strengthen spleen and stomach. Red beans, on the other hand, have the effects of clearing away heat and toxic substances, eliminating dampness and toxic substances, and are often used to treat diseases such as sores and ulcers.
To sum up, Hongdu and Hongdu are different in subject classification, shape, appearance and nutritional value.