Cannot Download DirecTV App on my TV

Is there a difference between DIRECTV app and DIRECTV stream.

Yes. DirecTV is satellite and DirecTV Stream is internet streaming. 2 different services.

If you are trying to stream Directv through their streaming service you can use a Roku device or a Fire Stick or you could get the Directv Stream Box that is the best in my opinion and the easiest to use because it is more like a traditional cable/Satelite box they are more costly than the Roku, or Fire Stick but they have more features and you can stream other streaming services through them.  You can get the Directv Streaming Box through Directv Stream or at any At&T store. Or if you are looking for a more cost-effective option then Roku or Fire Stick would be the way to go and you can get them online or through any retail store (Walmart, Target, Amazon etc).

Try these tips:
Check for app updates in your app store. If an update is available, install it and restart your device.
Check for device software updates and install.
Close and restart the DIRECTV app.
Reboot your phone or tablet.
Uninstall and reinstall the DIRECTV app.
Re-launch the DIRECTV app and try again.

Greeting,

Rachel Gomez

petergroft thanks for the unimportant info