Ray Kurzweil was hired by Google's current management to work at Google. How is this in any way analogous to Carmack's situation at Oculus, now Facebook?
The similarities are they are legendary & forward thinking technologists given a large amount of capital to pursue their passion and scale their vision.
Corporate title & organizition wise, they are different. Though I doubt Kurzweil worries too much about the current Ads, Search, Email, & Android platform. I would expect his role to be more forward thinking. I get the impression Carmack has a forward thinking role as well.
I'm not sure how true this is, but I recently watched an anti-google documentary about their book-scanning business and they said sources familiar with Larry Page claim that he had no interest in Google as a business but rather was attempting to achieve advanced AI through Google.