I have a Firestick and installed Kodi by myself. It's amazing, sometimes not reliable for watching the things that the mod above said can't be discussed. But for movies it definitely is worth it, don't buy one pre installed for an inflated price, as long as you have a computer and know how to follow simple instructions you can do it (one of the good resources https://www.firestickhow.com/kodi-firestick.html )

An Android box is just like an Android phone, you can install the apps that you want yourself.