What's the nutritional difference? How does the fatty acid profile differ? I'm sure someone can pull up a decent study - the USDA food database doesn't distinguish, of course.
I can't help you with the studies but I am assuming that you're interested just to see if pastured products are 'worth it' for you, and you want to see if you can back it up with peer reviewed science. I don't know about any 'studies', but... (more)