An important factor between Web 2.0 startups and "change the world" startups is the size of investment required. Web 2.0 startups are very cheap. Starting Tesla Motors on Y Combinator funding would be impossible. Apple was also started on a very small budget at a time when electronics was in a similar position cost-wise as the web is now.

What is different between most web 2.0 startups and Apple, though, is that Apple expanded an existing enterprise market to the general public. Cloud computing is having similar effects, but otherwise I don't see many similarities.