Nor button and Normal maps

Hello, I have been wonder whats the difference with the nor. slider and using a normal map.
I seem to get a normal map like effect when I use a normal color image, turn of the color value and crank nor. up to around 10
But I also have been playing around with normal maps, I enable them in the textures panel then turn on nor.
What is the difference in these two methods?

If you load anything other than a true normal map and select to Map to Nor, that images acts as a grey scale Bump map (afaik). The difference between bump maps and normal maps is explained in the Wiki here:

To add to what Matt said, Normal Maps (RGB) are much more accurate, since they change the direction and apparent face direction of the surface, giving much more realistic specularity and highlights, than using a black-white.

this might be a good addition to that page…to show the differences…