With 16-bit color, you can display 65535 distinct colors. With 24-bit color, the number jumps to 16.7 million. The problem is, if you are looking at a plain blue background on your desktop, you will not be able to see any differences. To see the difference, you need a picture with lots of vibrant colors (if you can find a desktop sized picture of a flower garden, that should do the trick). Then, when you switch to 16 bits, the picture will seem to lose some of it's clarity because as some of the colors are eliminated to reduce the color map, you lose some of the detail of the picture. The difference between 16-bit and 24-bit is not as stark as the difference between 8-bit and 16-bit, but there is a difference.