How so? Does Apple do not use the same buses, connectors and the same semiconductor fabrication process? So what's different after all? Their products are also produced in the same China from which Asus, HP and Dell hardware come from.
I think that what sets Apple apart from others is the fact that their products just works, no hackish measures are necessary to make it work in the most common configurations, no headaches to use, the iPod, the App Store, the integrated hardware and software, everything follow this, I would be glad if every company on earth followed this policy.
Metallic laptops tend to have wireless reception issues, conduct heat a bit too well onto consumer laps, have warping issues and can add weight. All of these problems have been present in macbook pros.
As far as the aluminium goes Apple has fetishised their materials choices for a long time and had as many hits as misses e.g. "Titanium" paint that flakes off, White iBooks that discolored, white iPhone 4s that they can't manufacture. Others generally don't bother as their customers don't want or need it. I'm not sure Apple users do before they are trained to by Apple.
Why did the iPhone run at such a low resolution while Windows Mobile and Android phones were coming out with 3x more pixels? Yet when they increase the DPI game slightly, brand it as a Retina Display, you think they're innovative?
Almost everything you mentioned was designed and built by other companies. Apple doesn't design their SoC, they don't design or build their touchscreens, they don't build their cases (though they aesthetically design them).
Which is probably a good thing because they need to focus on their core competencies (interfaces and visual designs), and leave the specialized companies to make the specialized solutions. When Apple tried to take a lead on hardware years back, they fell miserably behind.
Apple barely spends more on R&D than Dell.
http://www.businessinsider.com/chart-of-the-day-rd-for-tech-...
Apple has a hell of an R&D department. As far as I know, their retina display, unibody laptop manufacturing processes, and touch-based trackpad tech are unique to them. It's been shown a number of times that their touch screens are way more accurate than others, and somehow their battery life is quite remarkable compared to competitors as well. With the exception of the display and the unibody cases, the stuff I've listed here all require hardware and software to work closely together to achieve the perfect experience. It's areas like that which the PC makers will always suffer in if they don't change their approach, IMO.