Which heading is better?
The app is really lightweight & simple, but isn't that title too long to read and get user attention??
Neither, honestly.
Instead of describing what the app does, focus on the benefit for the user. What will they be able to do? Take notes, no matter where you are -- that's just a quick example, but it sells the idea of how my life will be better if I had your app. Does that make sense?
I hope it helps :)