Even if both are spying their users, the difference is that Google is offering great services for free (Maps, Documents, Earth, GMail, etc) whereas Facebook only give online space for crap and uninteresting things.
"For free." I guess that says it all. But not in the way I'm sure you meant it. Everybody knows there's no such thing as a free lunch/ride. You pay.
Google earth - the places you look at and pin.
Maps - the same.
Documents - what you type into them.
Gmail - what you send.
http://www.google.com/intl/en/policies/privacy/All datamined summarised and applied to your id profile. Depending on your lifestyle and income your customer value can be worth millions over your lifetime. In marketing this data is immensely valuable. It's your choice if you want to give it up "for free".
