No they are not! apps mostly use the internet for their data, but provide a richer UX than what a web browser can do. The internet is the underpinning of most apps.
But so much of the beauty of the Internet is its portable ubiquity; I can write a website once and it's available in much the same format to Windows, MacOS, Unix, iOS, Android.... you name it. Whereas in the mobile world we're seeing _millions_ spent on creating what are essentially platform-specific mobile data clients in parallel versions. They're barely even superior to what's possible with HTML now. This is madness.
A lot of people are making the same mistake in this thread. the web != the internet. By focusing only on the web you are leaving out other great, open technologies that helped the internet become ubiquitous. IRC, FTP, VoIP, IM, USENET, just to name a few.
Yes, HTML is a big part of the internet, maybe even the biggest, but its not the only one.
Obviously there are native app advantages to the end user beyond that, particularly given the slowness of 3G internet and the ease of making payments via the App Store. In many cases though its simply the same reason they also have Facebook fan pages and once had AOL keywords - branding.
Steve Jobs even started extolling the virtues of Apple's ability to "bring subscribers" to digitl publishers, and going by their latest announcement, Apple themselves regard their platform as being worth 30% of the value of the content, even to those who would rather process payments themselves.
It remains to be seen how far consumers and creators agree.
Beats me; so often IME it's true though. There've even been cases where I've installed the app and found I preferred the company's mobile website so used that instead.
Apps may not be the antithesis of the Internet, but the concept of an App Store arguably is. Internet = decentralized freedom, App store = centralized control.
The data is not the problem, the communication medium is not the problem, the issue is the control over the distribution channel.