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Hi,
Putting similitudes aside, the main difference I see is in the processor. The 15" has a 2.4GHz Intel Core i5, and the 13" has a 2.66GHz Intel Core 2 Duo.

What is the advantage of having the "i" processors over the Core 2 Duo, and for what applications are they meant?

Is it likely that the 13" MBP may have an "i" processor for the next update ??

32nm vd 45nm, smaller, cooler, more powerefficient supposedly
hyperthreading (>= i5)
turboboost on CPU and GPU
DDR3 memory support
+/- 25% faster (mostly on i5 or better though)
theoretically more resell value
i5-520m being almost as expensive as a C2D p8600 (it's $16 more expensive) and even cheaper then the P8700
 
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