It's magnesium and not aluminum. Its keyboard is color-matched to the metal. Its screen detaches. Its trackpad doesn't take up the entire space between the keyboard and the edge. Its chamfered edge is the full width of the trackpad so you don't hurt your wrist. It has the Surface Book's signature "fulcrum hinge" and the associated gap. Its display has air vents. Both the base and the display are the same thickness.

But it's a metal laptop that comes in two sizes, so it looks like a MacBook to some people.

This... looks nothing like a macbook. It's got a matte metallic frame and a black bezel, but that's about where the similarities end as far as it looks to me.

Are we looking at the same thing? It looks incredibly similar to Macbooks.

Aside from the colours/finish, what's the same? Looking at the macbook in front of me and the image here they're totally different: the hinge, the keyboard, the vents, the ports, no touch bar, no speaker grills etc. Everything else is just laptop fundamental design, e.g. it is primarily composed of two slabs and a hinge, with a keyboard and trackpad in ergonomically optimal places.

No, macbooks close flat. This closes into a wedge, with the rear hinge approximately one-half-inch higher than the front when closed, with a gap between screen and keyboard.

In addition, macbooks are bezel-filled and sleek, where this emphasizes straight edges. Horizontal corners are rounded, but vertical edges are square.

Keyboard is also very square, instead of the rounded rects favored by macbooks.

About the only thing that's the same is that they're both aluminum white laptops.

I think what you mean is, "why do so many high end laptops have thin, metal, unibody chassis?"

But, when you ask the question that way, it kind of answers itself. People like metal, because it feels more high end than plastic. Unibody chassis don't need to be fastened together, which is good for manufacturing and looks. People like thin laptops because they are more portable than thick ones.

Unibody helps make it thinner, too. A traditional laptop design had to have both structrual components and outer casing -- unibody designs do both and save space

It's technically not unibody, the keyboard (and its GPU) detach.

You may also find that the unibody MB has the screen portion housed in a different aluminum block than the body. Semantics are dumb.