It's different because Comcast/Verizon don't have your email and your calendar and your web surfing habits and your voicemail and your text messages and your contacts and did I mention your email?
Many people use Comcast/Verizon-provided email services. Most people use them for their home voicemail too. And they can absolutely see your surfing habits if they want to -- excluding encrypted communications, of course.
It's a great point. I've always shared the same suspicion, but there hasn't been any instance yet, at least in the public eye, where google has abused my personal data.
I think they've just realized for everyone to "move to the cloud", we need internet that makes it possible.