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.

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.