As a macbook owner myself, I can tell you you have to use one regularly to notice that the build quality and attention to design is just much better.
Solid unibody aluminum. Auto-dimming display. Backlit keyboard. Great battery life. A trackpad that is pleasant to use and works for scrolling, gestures, and moving the mouse. Tight OS integration with all of these hardware features. It's pretty clear whoever designed these features actually used these features. I've used cheap laptops before and they get produced with shitty features like fingerprint sensors that barely work. It's as if no one actually bothered to use the features they slap onto cheap Windows laptops, because if they did, it's pretty easy to notice how useless or unusable a lot of the features are.
Most people spend the money on a commodity windows computer because they need a computer. When people spend the extra money on a mac, they do so because they want a mac. Point being, people buy a mac and pay the extra because every feature they include has a purpose and has been tested to be actually useful and not just a marketing gimmick.
Thinkpads have better build quality than most PC laptops, though I'm not sure whether on par with the unibody design in MacBooks. My own experience is that my T410 overheats when doing serious work like encoding video. The case is sturdy, but not airtight. It's supposed to be able to withstand spills, but I've never had to find out if it really can.
