One could write a book on that topic. My stance is that they prioritize what and how they do differently than most competitors, and that would be end user experience and polish.
E.g., the iPhone UI's smoothness was a result of their prioritizing smoothness over other factors, like ease of implementation. If you look at how they did it (view objects are backed by GPU rendered layers), it's not really developer friendly. Because developer friendliness is not their priority, at all.
So, what you should get from Apple is the most polished experience, and they exert a great deal of control to make sure that the designed experience actually arrives at the end user. They got this really right with hardware, but they still struggle with the software part. Sure, most software Apple produces is beautiful and works really well. But things are crumbling. Looking at the various fiascos - Maps, Me, then iCloud Syncing, increasing number of problems with OSX quality - this controlled approach does not seem to work that well on software. You can control all possible states and usage scenarios of a physical device, but good luck with that on a OS consisting of 4 billion bytes, or a massive neural network (Siri). IMO they need to let go and open up at the software side.