For me, Plenia, the question is like someone asking what's the difference between a Ferrari and a race track (or a lion and a zoo) - you can talk about one in relation to the other, but they're completely different things and can both exist independent of one another!
NLP is (officially) "an attitude and a methodology which leaves behind a trail of techniques." So I can coach people with an NLP attitude and utilising NLP techniques, and I can also coach them from any one of a hundred different points of view using thousands of different techniques. Coaching (for me) is the process of bringing out the best in someone and making the best better. It is a context in which a coach can 'be there' for a client in a way that makes it easier for the client to reach their goals. NLP is (for me) a wonderful set of filters I can work from and tools I can use that tend to make me a more effective coach.
Hope that helps, or that if it only serves to muddy the waters you find it to be "quality" mud...