the big difference between the two is that they are very far from doing the same thing…
1st the uv map is a map which basically holds your colour information of your model… the uv map has boundries and border edges based on the structure of your model. so this is why your colour info is kept in between the line of your model’s uv map.
2nd the normal map is a map based on the structure of your uv coordinates accept that it is used to give your model the illusion of more detail than it really does have.Say for instance if you made you 20 million bolly model and you create the normal map of the 20 milion polys then you can take your lowest level model and use that to base the normal map on…this allows your low oly model to have the same appearance of the 20 million poly model.
Hope that clears it up for you.