I think that's the key, which makes them fundamentally different. So, in the _very_ narrow scenario in which you happen to join a company that will IPO and that you're there from pre-IPO until post-IPO, yes -- they're nearly the same; you really just benefit from the difference of the strike price and public price. If you've spent time at the company, vested your options, and want to leave for just about any reason, it's nothing at all the same. I posit that a vast majority of startup departures fall under the latter scenario.