While they may just be titles, my experience has been consistent with their titles. Apple representatives you see once a year at WWDC, while Google representatives you see at Google I/O and also at a number of Google-hosted events year-round, including the regular videos they put out (and the "office-hours" type Hangouts they have so that you can actually talk to them and get your problems resolved) - just look at all of the events they have scheduled on the Google Developer Events page[0] or all of the videos they have on their YouTube channel[1]. I've also seen a lot of them give talks at tech conferences, while Apple employees are rarely seen at conferences. And you can see that Google's Developer Advocates really do talk directly to the actual teams directly and file bugs against them when necessary on behalf of developers everywhere. It's a system that has worked pretty well in my experience.
I will also agree that Google's Developer Advocates don't care too much about what platform you're using and just want to help you. I've been to a number of Google-run technical workshops and codelabs, and the people there are willing to help you with whatever problems you run into, no matter what it is.