Native is for both Android and ios. Web too, although hybrid apps are refused in the Apple appstore nowadays as far as i know.
Nano flows can be used in all scenarios.
For xpath, you really need to consult the training materials. All training materials and docs are in english, the forum will not be a good replacement for these materials.
I hope this helps.
In a nutshell:
Hybrid uses a phonegap browser to show regular responsive webpages on your device.
Native apps are closer to the devices internal systems.
But this is a gross simplification and many factors come into play. For details there was a good session at Mendix World on the topic: https://www.mendixworld.com/session/establishing-your-mobile-architecture-strategy/