John, as a tech geek and an investor in these companies, I am often at odds with the common opinions of non- investors here in these tech forums.
IMO, you are correct to state Google is an advertising company. IMO, Google's online advertising business model can never be compared to Apple. It is better, today, to compare with Facebook. While Google does develop OS Android, this is basically a lost leader for their ad revenue stream. Most recent qtr report issued by Google admits a problem in their ad revenue with the shift to Mobile advertising. The run up of it's stock in the recent past was mainly due to a misconception that Google had this under control. The loss of market cap with Facebook same time period was because a qtr ago, Facebook admitted they were having trouble with this. Then this most recent report Zuk stated they had gotten the problem under control and began to improve revenue on mobile. I have no doubt that Google will follow Facebook's lead in this and also resolve the technical problem of converting ads on mobile to $$. Time will tell on this.
By contrast, Apple is not an advertising business at all. It is a hardware / software and apps company. Comparing these companies, IMO, is not appropriate at this time. If, in the future, Apple introduces it's own social media app and tries to monetize it with a big advertising business model, then yes, it will be in direct competition with Google and Facebook.
Apple is planing to get into a new offshoot of itunes, streaming radio, and this is a direct target at Pandora.
While we agree that Android is a very healthy eco system, this really has more to do with android device makers and app creators, than generating direct profits for Google. One problem I see is that as Facebook is a direct competitor for ad revenue and it runs on the android device, it, in essence is robbing Google of those ads. As an ex TV ad guy, I eagerly await to see how Google and Facebook handle this now that we are on the cusp of resolving the tech problems with monetizing mobile advertising. Meanwhile, Apple, is on the advertising revenue sidelines and has nothing to lose, only to gain, with Facebook monolithic revenue stream.
Disclosure- I don't own any FB or Goog at this time. Apple is my main holding. I only state this so people will know why I seem to favor Apple. It's about the money, not their products.