The cover's essentially the same (although the reflection of the crossword in the alienhead here is a little freaky looking). Alienware has swapped some connectors and moved them around; in this case, more are on the back where they're less likely to get tangled up with your corded accessories, like the mouse.
However, it's now steel reinforced with better travel and more flexible programmable lighting. It's really quite nice to use for both gaming and writing, though it feels more membrane than mechanical. And it seemed to handle concurrent input for running, jumping, firing and eviscerating pretty well.
There's a built-in mic, IR camera for Windows Hello and a 75-degree 1,280x720 webcam. In addition, an IR emitter is used for sensing, and the Tobii Aware software uses it to detect your presence and change power-saving settings when you're not in front. The 15-inch doesn't have Tobii Eye Tracking, though; only the Alienware 17 does.