Nowadays you can find Amazon pre-installed on almost every Smart TV's and media players. So you may ask yourself, why buy a Amazon Fire TV or Fire TV Stick when my Smart TV already has Amazon built in? Won't you just get the same thing?
While the basic Amazon App built into the TV supports basic playback of all your Amazon movies and TV shows, only the Fire TV enables you to access premium features like games or using the Amazon Video App on a smartphone or tablet to remotely play content.
To demonstrate this limited functionality of the built in Amazon App in a Vizio M-Series 4K Ultra HD Smart TV, I played a video from the Amazon Fire Tablet like the HDX8.9. While playing the video, there is no option to play it on any other device other than the Fire Tablet itself even with the Amazon App opened on the Vizio.
The same applies with the LG 4K Ultra HD Smart TV with webOS 2.0 (2015). Again, there is no option to remotely play the movie being shown in the Fire HDX8.9 tablet to the Amazon App opened on the LG TV.
Even if you download the Amazon Video App on a Android phone like the Micromax Canvas Knight 2, there is no way to play the video shown on the Video App to the Amazon App opened on a Smart TV or media player like the Roku 4.
With Amazon software available on multiple devices it all can be quite confusing. If you want the most seamless Amazon Video experience packed with premium features, it's easiest to stay with Amazon products like the Fire Tablet and Fire TV.