Features : Apple TV -vs- Apple TV app on Samsung Smart TVs

Is the Apple TV app on Samsung Smart TVs the same as a separate Apple TV ?

Can the Apple TV app on Samsung Smart TVs run other Apple TV apps, such as Netflix, Amazon Video etc.. or does the Apple TV app on Samsung Smart TVs just run iTunes pay per view movies / TV, and Apple TV+ subscription content. Whilst leaving Netflix, Amazon Video etc as standard "Samsung Apps" ?

No, the Apple TV app on the Samsung Smart TV does not allow you to run other Apple TV apps such as Netflix, Amazon Prime Video, etc.

The Apple TV app on the Samsung Smart TV allows you to buy and rent movies from Apple, subscribe to the Apple TV+ service and Apple TV-channels.

Here's Apple's instructions on getting it setup:

https://support.apple.com/en-gb/HT209440

If you want to use services such as Netflix and Amazon Prime Video, then they must be installed as "Samsung Apps" independently.