Both SetPixel and SetPixelV perform the same the action but SetPixel is a little bit more accurate and returns the color that the pixel was changed to (neither function is 100% accurate when setting colors) . SetPixelV sets a pixel to close approximation of the value you specify (again not 100% accurate) but it is a little faster than SetPixel because it does not return a color, it returns 0 if it failed and 1 if it was succesful in changing the pixel.