That what helped Apple to stand out the crowd was much stronger marketing muscle (started to grow in the 8 bit computers era) and making no trade offs for crappy hardware like caring about running on systems with 4 MB of RAM. In long term it helped making them look like a quality and luxury brand. (Same applies to Apple vs Windows).
No, what made Apple stand out is that the platform itself was very, very, very compelling.
People wanted to program for it badly enough that they were willing to jailbreak the devices using systemic exploits to do it, and then work on developing an SDK for it, to the point of reverse engineering the APIs for all the frameworks on the thing, and then making modifications to the scratch register usage in the compiler, because Apple did not use the standard (at the time) ARM ABI or calling conventions.
Jailbreaks initially came about so as to rewrite the baseband seczone and then put a new (valid) TEA signature on the thing, so as to remove the carrier lock, since Apple sold the things into a limited market, but people *EVERYWHERE* wanted an iPhone. It got so bad at one point that Apple limited the number of iPhones you were allowed to purchase, and entire shipments were hijacked at gunpoint.
That never happened with Nokia phones. Ever.
When Steve released the thing, the Application story was that "You'll use web apps. Period.". Steve was deathly allergic to the idea of building another Apple Newton, and wanted it to be a closed system.
Only the damn thing wouldn't stay closed, and when it surfaced that the boot ROM had the same buffer overflow flaw in the signature validation code that was in Samsung and Sony devices which used Samsung OEM'ed processors, it was "game over" for at least two years on spinning new silicon.
Seriously: No one ever bothered with the Nokia phones.
Even if there had been a capability baseline (all the Apple phones has the same sensor capabilities, the same screen aspect ratio, and, initially, the same screen resolution) so that you could write one piece of code for a Nokia phone, and it wouldn't be missing features and/or run like crap and/or have to scale everything into ugliness due to using whatever the cheapest bulk available LCD resolution and aspect ration the thing had when Nokia was pricing parts right before going to manufacture -- the damn things were not compelling enough that people *wanted* to develop for them.
The only people who developed for Nokia were the ones the phone company paid to put simple games on then through the phone company stores, or the ones that Nokia solicited themselves, or the *very few* vertical market applications which would fit on the things and remain useful.
Nokia phones were crap feature phones with a JVM "in case", and while you *could* write binary applications for them, it was a massive PITA, and they weren't portable between models, and Nokia didn't pre-release models to developers -- which is kind of what you have to do, if you are going to be shipping a bunch of hardware incompatible devices, and the apps would only run on the older devices no longer being built.
Build a compelling product that developers want to develop for, and they will *break into* the thing to do it, even if it means sending the device to someone in Korea who's willing to remove surface mount chips to get at the JTAG port, and then reattach the chips to the device in a reflow oven, because he happens to have one, because he's an engineer at Samsung who works on Samsung phones, and the things are more compelling than what his company has him working on most of the time.
*That's* why Nokia took the dirt nap.