Black beans and soybeans are close relatives and belong to the soybean family, but there are differences in varieties and similar nutritional components. Therefore, black beans and soybeans are rich in nutrients such as protein, potassium, magnesium, calcium and B vitamins, as well as soluble dietary fiber and isoflavones. The difference is that soybean contains a small amount of carotene, while black beans contain chlorophyll and melanin, which are all beneficial to health. Compared with soybeans, black beans have slightly higher contents of protein, potassium and vitamins, and have stronger functions of clearing fire, benefiting water and resisting oxidation, so black beans are better.