If it's anything like what happened with others (like Eric Schmidt), Chairman is basically "you're out from day to day stuff but we'll give you a pot of money to say you're still senior and still here, to save face and the stock price, while you give a bunch of talks for the next few months"

So yes fancy title, but basically, someone who can move the stock price is quitting and we're trying to ease the perception of it.

Chairman is a stepping stone for a retirement/resignation. Apple's Tim Cook. Google's Eric Schmidt. The list goes on.

But Alphabet is just a holding company, what does Chief Scientist of Alphabet even mean?