In fact, this is because the mesophyll of leaves contains a lot of chlorophyll, which can help plants to carry out photosynthesis, and it is these chlorophyll that make the leaves look green. The mesophyll cells in front of the leaf are densely arranged, with more chlorophyll, and the mesophyll cells in the back of the leaf are loosely arranged, with less chlorophyll. In addition, the front of the leaves receives more sunlight every day than the back, and the leaves are greener where there is more sunlight. It is these two reasons that make the colors on both sides of the leaves different.