Appearance: Black beans are small in shape and belong to soybeans. Like soybeans, they have higher fat content. Black kidney beans are bigger than black beans, belonging to starch beans with high starch content, and belong to the same category as red beans and mung beans. Inner kernel: The inner kernel of black beans is different from that of black kidney beans. The kernel of black beans is generally yellow-green, while the kernel of black kidney beans is white. Color: black beans are dull, black kidney beans are bright, black beans on the left are dull, and black kidney beans on the right are bright.