An in-depth comparison of Apple TV vs. Google TV has been made by the good folks at Cult of Mac.
The article concludes, "Each device has its strengths and excels in individual areas; Google TV boasts more content sources and applications, whereas AppleTV has a remarkable operating system and access to the popular iTunes Store. It all boils down to user experience, and which device will better suit you. Those used to AppleTV’s simplistic user interface and familiar features may find Google TV slightly overwhelming. With it’s numerous content sources and long list of OS features, the average user looking for simple home entertainment may find it a pain."
We would strongly urge that you click here and go to the actual article which has a chart and other direct comparisons between Apple TV and Google TV.