1. What Apple TV Can Do: Apple TV is able to stream from iTunes, as well as some online services such as Netflix. It can stream local content from PC or Mac as well. The ability to stream local content is a big plus for Apple TV.
Nexus Q Can't Do: With the Nexus Q, you are only able to tap into content on the Google Play store and YouTube. Hence, you will only be able to play movies, music and TV shows bought off the Google Play store. So no services like Netflix or Pandora can be used; these applications are ones that consumers have grown accustomed to using.
2. What Apple TV Can Do: It prices itself at $99 but offers the equally vast amount of content through iTunes, and the same services that the Nexus Q provides.
Nexus Q Can't Do: It can't justify its price at a whopping $299, with Apple TV almost providing the same quality of content and services, maybe even more but at a price of $99.