A WebView is just that - a web view. A WebView is just a fancy name for a browser window embedded inside an app.
So PhoneGap applications are technically "hybrid apps." The WebView portion of the app is native code - but that really is just a technical nuance with no implications for performance (in fact, the performance implications are negative), because it's like claiming that your website is "native" since it runs in a browser (say, Safari) and the browser is written in native code. But the non-native portion of the app is what goes inside the WebView (HTML/CSS/JS).
So PhoneGap applications are technically "hybrid apps." The WebView portion of the app is native code - but that really is just a technical nuance with no implications for performance (in fact, the performance implications are negative), because it's like claiming that your website is "native" since it runs in a browser (say, Safari) and the browser is written in native code. But the non-native portion of the app is what goes inside the WebView (HTML/CSS/JS).