Admob vs AdSense

According to your last question: Users click ads in mobile apps much more than on websites and it is much easier to make money on mobile platforms. It is quite harder than 1-2 years ago, but you can still get through. If you want to make money on apps Android is a very good choice, but if you would prefer to sell your apps choose iPhone.

Simple answer:

Adsense: For websites. If you login in adsense website you'll read "Show ads on your own website".

Admob: For natives or hybrids apps ("mob" comes from mobile). This would be your case. If you login in Admob's website you'll read "Earn more from your apps the smart way".
If you use Cordova/Phonegap (hybrid) you should use this plugin: https://github.com/floatinghotpot/cordova-admob-pro
For native apps take a look into this: https://firebase.google.com/docs/admob/android/banner

In both cases you should add an app to start to monotize with in your admob account and a bank account as well (you'd need to earn at least 70€ for first payment).

AdMob is used for native applications, so you should use AdMob in this case. AdSense is used for mobile web applications.

The amount of revenue in an ad-based model really depends on the amount of users and ad requests. Ads can be a good stream of revenue but you do need the user base for it to take off.