Couldn't tell you the specific details, but I know that the 208GPs are very sticky when warmed up, but they take a while to get there and are a bit of a nightmare when cold!
The profile on the 208GP's is harsher for a start, and will turn a lot quicker, plus I think the tread pattern of the 207's runs pretty much to the edge of the tyre, whereas the 208GP's and 207GP stars don't.
GP's are stickier, but do need heat in them, which to be fair most tyres do, life time will be reduced, personally I prefer grip to durability
ive had a pair of 208's on for about 500 miles, and have to say thay are the dogs, seem to grip no matter what and only take a short time to warm up, have gone to these from supercorsa's and they are much better for road riding. the supercorsa's never seemed to totally heat up when on the road. one very satisfied customer stew