They are pretty similar. The major difference is the interactivity. A web page will let the user to consume the content. For example read the news, purchase an item. Good examples are: news pages or online stores. A web application would let the user to update the content. It is like a desktop application but accessible through web. A good example of web application would be your online bank or google docs

It is impossible to provide any estimate without knowing more details. The price highly depends on multiple factors like functionality, design, expected usage count and/or infrastructure requirements. Please contact us with more details and we will provide an estimate

Both are installable mobile applications that run in your smart device. The difference is that hybrid applications are technically running on a special application which is working like a layer between mobile device's operating system and the hybrid application. This most often limits the capabilities of the application and most typically hybrid applications does not feel as smooth as the native mobile applications

It depends on the website requirements. However, you will always need to pay for a website's hosting and most typically a domain name and email associated with it

It depends on the mobile application requirements. However, at minimum you will have to pay for publishing it to Google Play Store or Apple AppStore. Google Play Store has a one time fee of 25$. Apple AppStore has an yearly 99$ fee