There's often some confusion whenever Google releases a new product that overlaps one of their existing products, and Android TV (specifically the Nexus Player) and Chromecast is no exception.
The devices are appropriately named, the Chromecast follows the Chrome model, the device is nothing more than an extension of the devices you already own - it has no real configuration or customization of its own beyond some basic things like WiFi access and an odd Guest mode for when you trust people enough to send stuff to your TV but not to let them on your network.
The Nexus Player, on the other hand, is yet another Android device. It's closer to the Roku/Fire TV model where individual apps are required to access content, but it also has a Chromecast built in so it's almost a superset of the Chromecast (see below). The downside is that it's tied to one Google account, hopefully that account is the one who purchases the content and not the one you get personal email on. The upside is that there are plenty of things that the Chromecast will never be able to do, streaming action games is much harder than just installing the app. Installing the Nexus Player as a Chromecast is feasible (I'd recommend a throwaway Google account), but you don't get a huge amount out of it unless you want a little computer tied to your TV.
|Apps||None, they're not needed||There is a section of the Play store dedicated to Android TV apps.|
|Updates||Automatic and silent||Similar to Android phones|
|Remote||Uses TV remote||Uses TV remote or Bluetooth remote included. Third party remotes possible.|
|CEC Support||Power on TV, switch input, play, pause. Some app incompatibility (Netflix, Pandora).||All of Chromecast plus D-pad including select as play/pause toggle, fast forward, rewind, skip forward, skip back.|
|Content Selection||Device-only||Device (only Castable content) or app|
|Input||Who needs input?||Onscreen keyboard, device remote using device keyboard, USB/Bluetooth keyboard.|
- Mostly, Netflix, for example, requires that the app is installed and logged in, some other apps have had non-Chromecast behavior.
- A USB-to-Ethernet adapter may be used to hardwire the Player to an Ethernet port.