
Apple kindly lent me a 13-inch MacBook Pro for a fortnight to have a look at. I haven't done a proper evaluation of a new Mac since the MacBook Air, so I'd used a couple of unibodies but not to evaluate seriously, and this had the added fillip of being the new 'Pro' version.
This one had 4GB RAM and a 2.53GHz processor. A few other details differed too - the 13 has 3MB of L2 Cache and a 1.07GHz bus speed.
They both have 2x USB2 ports, but the 15 has FireWire 400 and 800 plus an ExpressCard slot for some easy expansion (for which Sonnet's ExpressCard 34 is a particularly good addition, adding another two FireWire 400 ports and another USB2.
The video cards are different too. The older 15 has an NVIDIA GeForce 8600 GT with 256MB VRAM, the 13 has NVIDIA's GeForce 9400M with 256MB VRAM. Both cards support Quartz Extreme.