With all the glass and pixels out of the way, we immediately pick out some subtle updates.

First, the logic board has grown—encroaching on territory formerly held down by the right speaker, and even expanding towards the fan a bit.

Even more notable, there's a conspicuous heat sink mounting plate sprawled out in the middle of the board. Funny, the old heat sink didn't need one of those...

Lastly, near the center of the bottom display bezel, just beneath the glass, there's a microphone! Whose ribbon cable routes right over the top of a screw, which is pretty weird.