Well, I find that the difference between a teacher and self-teaching/experience is the practicality of it all. You don't ever follow the instructions on the back of a box of coffee because it'll turn out horrible and everyone has their tastes and quirks. You need to be taught how to read and write because there is one definitive way to do it, and it is usually the most effective way to learn.

With fighting, I divide it like this. A martial artist versus a street fighter. The Martial Artist has learned a certain form that has been passed down for generations. It's a fighting style, but its treated more like a dance, not normally deviated or altered unless they are in a grave situation.  On the other hand, a street fighter is flexible and normally aware of their surroundings. They alter and change all the time to fit where they are the best.

But when it boils down to the core of things, all of it is preference.