Unlikely that there's a difference. It wasn't Apple (or Steve Jobs Himself[tm]) that invented the capacitive touch screen and made it available in large quantities (ie. mainstream compatible).
There were prototypes at many (probably all) mobile vendors exploring the capabilities unlocked by that technology.
Apple "merely" was boldest - but then they hadn't to consider how a new HCI impacts the brand, since they had no old mobile HCI that mattered.
Things might lag half a year or so due to this, but someone, somewhere would have kicked off the "touch revolution" in about the same time without Apple. Maybe even RIM or Nokia.
Funnily, Android/Google was in a similar position as Apple, in about the same time (new market to enter, knowing the old style mobile HCI and touch, having prototypes for both) - and they seemed to prefer the old style for now.
In a world without iPhone they probably would have waited for one of the big guys to introduce touch, and then followed quickly.
Google wasn't as confident about pushing an unproven HCI onto users as Apple was.
Capacitive screens were already used by one terminal, I think an LG phone. But the iPhone put something different in the market: multitouch and gestures. Some things like slide to unlock or pinch to zoom seem trivial now but they weren't really product of the normal evolution of phone interfaces. Locking the screen was done with a hardware button because it was deemed safer, zoom was double tapping in the part of the image you wanted to magnify.
Had the iPhone not been introduced I doubt small little details like these would have changed at all, and there are tons of these small subtleties in the current smartphone OSs.
I've seen two of the pre-iPhone touchscreen OSes without a sliding keyboard or anything like that and they both sucked hard. I owned a LG Prada and knew someone who owned a Samsung F490. They were both terrible, I would've rather had a classic phone than a Prada and my friend who owned the Samsung F490 handed it down to his daughter and replaced it with a classic phone. Lots of people thought that smartphones with touchscreen would behave like the iPhone in its ads except that it was far from the case.
I don't think anyone but Apple could've kicked off the touch revolution. RIM and Nokia ? they only switched course after the iPhone. Nokia's stayed in the comfort zone with Symbian for far too long and didn't have any innovative OS for smartphones and RIM was making candybar, fat and ugly phones with basically just one target audience : people who constantly use email. As long as most people use cases of mobile internet came from email software, RIM wouldn't have felt the need to innovate at all.
The iPhone was really the first touchscreen phone I ever felt comfortable to use. People who made the comparison to the Prada when they were saying that Apple didn't innovate obviously never touched a Prada. It's one of the shittiest phones I've ever used, and phones with keyboards were much better than this. The tactile feel of the touchscreen wasn't good, it lacked precision and the whole interface was programmed in mobile flash. It lacked any advanced feature and couldn't install apps outside of J2ME crap, unlike Windows Mobile. It didn't even have a real web browser.
It's been proven with the new Windows Phones, and new BB os, that you don't need to copy Apple to make good touchscreen OSes. I can understand the anger Apple felt with some Android vendors, and it is true that Samsung even changed the stock Android icons on some of their phones to match more closely the look of the iPhone (WHAT exactly is wrong with the stock android UI ? for god's sake, don't mess with something that already works great).
Samsung is renowned for being copycats, and not just in the mobile phone market. The trial itself revealed that they were targeting Nokia before they changed course to target Apple. But almost all of their electronic division consists of nothing more than being shitty copycats. Their digital cameras aren't anything to brag and Samsung was so late to the DSLR market (mostly hybrids in their case.. uh) that I can't understand why one would ever consider them seriously. Their whole home appliance division consists of nothing but copying other products, they never made anything worth a look.
There were prototypes at many (probably all) mobile vendors exploring the capabilities unlocked by that technology. Apple "merely" was boldest - but then they hadn't to consider how a new HCI impacts the brand, since they had no old mobile HCI that mattered.
Things might lag half a year or so due to this, but someone, somewhere would have kicked off the "touch revolution" in about the same time without Apple. Maybe even RIM or Nokia.
Funnily, Android/Google was in a similar position as Apple, in about the same time (new market to enter, knowing the old style mobile HCI and touch, having prototypes for both) - and they seemed to prefer the old style for now.
In a world without iPhone they probably would have waited for one of the big guys to introduce touch, and then followed quickly. Google wasn't as confident about pushing an unproven HCI onto users as Apple was.