I need help to know the difference between these two.
In a mobile app, the UI uses the native UI controls set of the platform you are running in (ios, android) and all the logic is run in the device itself. You "decide" if your app can be run without internet or not, amongst other things.
In a WebApp, you basically create a platform independent app, that uses the UI controls of the framework you choose to create the webapp with. Accesss to the webapp is done by browser, and your logic control is done on server side. To deploy a Webapp you need a VPS server, and the end user MUST be able to use internet to use the app.
These are the main differences, but not the only ones... Should be enough though to help you understand the differences