There is not a lot of vertical integration in Apple's physical supply chain. Screens are sourced from Samsung (or have been last time I checked), phones are assbled by Foxxcon (same as above, might have changed).
Managing all that is what set's Apple appart from others. Besides brand, design and such. I'm in no position to judge the software part.
Now it's their vertical integration and just how good they are up and down the stack compared to the competition.