Web
Both web apps and chatbots are accessible on the web using the published URL. Depending on the app visibility, people with access can use the app using the published URL.
You can run the app without publishing using the Preview tab in the app builder page. This allows you to test the app before publishing. If the app is set to private without any shared users, only you can access the app.
Web app renders a form corresponding to the input fields in the app. When input is submitted, it streams output to the browser. The output is rendered using the output template.
Chatbot apps are rendered as a chat application that a user can have a conversation with. If the app has more than one input, the chatbot will render a form which takes all the input fields. The chatbot will then render the output template for each response.