You can find out here. I was using the 32 bit Pi 3 one. I did check the checksum.

https://www.home-assistant.io/hassio/installation/

It's using a Docker container for the app. I assume that gives them more control, but it restricts the user a bit. Before when I used their Hassbian distro I would install the X10 app from source, but Hass IO does not allow that.