Differences between bootstrap and Ionic

You can't compare Ionic and bootstrap in such a way.

Ionic is for building mobile apps and has a lot of building tools integrated. It is built upon bootstrap for styling content and cordova for building the actual app. But you can't create normal web apps for production with it.

Bootstrap itself is only a simple framework for styling html elements.Cordova is for wrapping up webpages in a native app context.

Bootstrap is cross platform UI components for mobile/web applications.

Ionic is Cordova + Angular + Cross platform UI components + Native plugins.

The Ionic Framework has similar goals in that we want to help promote recommended design patterns and document best practices.

Ionic combines AngularJS (JavaScript by the way) with HTML5+CSS and uses Cordova to access native device functions.

So effectively you are right that it is similar to Bootstrap but it they claim that Ionic is built for the devices of today and the future, not for devices built years ago. It’s focused on native app development and not mobile website creation.

Learn more differences here.