When publishing an HTML5 application, you rely on the web browser that's installed on the computer (or device) of the student to render the course. That is, if the course is viewed on a tablet, your student needs to open the web browser that's installed on the tablet to see the course.
When using the Publish for Devices (app) feature of Captivate, you can generate a native mobile application from your eLearning content. This means that your course could be distributed by an app store (such as the Apple App Store for iOS or the Google Play store for Android) and will be installed as yet another app on the device of your learners.
To convert your course into a native application, Captivate relies on the Adobe PhoneGap Build service. This online service can convert any HTML5/CSS/JavaScript web application into a native mobile application. PhoneGap Build supports many mobile platforms, including iOS, Android, and Windows Phone.