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.
Yes, HTML is a big part of the internet, maybe even the biggest, but its not the only one.
If this were really the case — not just in a spec-sheet way but in a user experience way — why are all these companies making apps?
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.
If webapps had the same payment/installation procedure, they'd take off like a rocket too. (Given HTML5's local caching and the like.)
For instance, Chrome Web Store offers a payment/installation for web apps, and it doesn't seem to be taking off like a rocket.
The data is not the problem, the communication medium is not the problem, the issue is the control over the distribution channel.