Angular 1 needs the angular.js file, which will be included in index.html so that it translates the directives into a browser-friendly form.
Whereas angular2 uses typesscript, in which a script type compiler compiles or translates typescript code into a clear javascript / ecmascript browser that will be displayed on the screen.
angular js " " , angular 2 javascript/ecmascript. , , javascript/ecmascript .