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”.
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.