the nature of MMA

[Little Apple]

I have a question: Hopefully long enough ago not to draw attention by this question, I read something very interesting that was posted by a respected instructor.
Someone had started one of those "I want to learn some MA for self deffence and a little because I want to be cool. What style is most effective?" Most people, including myself, said that for straight SD a good choice was MMA. At least insofar as mixing a decent upright striking art with some good grappling, and if you have a little extra time, a weapon (insert brief debate over what specific styles fit those catagories best). Well, this instructor disagreed and said MMA was no good as SD. I said that I thought mixing it up gave a good understanding of motion and options and tools. The responce was something like "What are you going to do? Put them in a submission hold until a cop drives by?"

So I wanted to swich forums briefly ask the MMA guys if most of what you learn would end up like that for SD. Just out of curiostiy. I just feel like the places I've been to mix the grappling up and say "this is the rules for this system, so don't do it in the ring, but here's a nice place to take his ear." Plus they encorperate MT, boxing, trapping, etc. I don't feel like MMA always comes down to submission holds, but I thought I'd throw it to the community and ask what the larger MMA world looks like.

[Little Apple]

OK, let me change this to get some answers:

What's the difference between MMA and JKD?