My understanding is that "Contacts" is the address book, but the contents of the address book can be synced to different sources including Google.
I just got the syncing to work again though, and hopefully it will continue to work. In a nutshell, I had to turn off the google sync, close address book (Contacts now in Mountain Lion), then reconfigure google sync. Here is what I did that seems to have straightened it out:
- Syncing stopped working even though my Address book was connected to google, and had been working fine for many months.
- In Address Book (Contacts) I Unchecked "Synchronize with Google" to disconnect the sync
- I closed Address Book to ensure it didn't cache anything.
- I reopend Address Book and in Preferences, I checked "Synchronize with Googe", and supplied my google account information again.
- Note that there should now be a sync icon in the menu bar. Clicking "Sync Now" from here will force the sync and you should then be able to immediately see the results in the browser.
- The sync process started, and it warned of duplicates - I picked Google as the source (I trusted that version more than my loca copy), and let the sync happen
- Checking directly on Google in a browser showed the sync seemed to be working
A possibility that may have caused this problem is when I configured iCloud, there is the ability to sync Contacts with iCloud. I may have clicked this (before deciding that was a bad idea) and I believe this turns off the Google sync but likely doesn't turn it back on again when you stop syncing contacts to iCloud.
Hope this helps...