You can apply white wall paint to the area with color difference, then brush it once a day for about 4 to 5 days. If there is still a color difference after 4-5 days, apply putty to the area with color difference. After the putty dries, sand it with sandpaper, then apply white latex paint. In addition, when purchasing latex paint, try to buy the same product from the same batch; otherwise, the color of the finished product may have a color difference.