Key points about AngularJS Directive and custom element using Polymer.

Creating custom element is achievable by creating a custom Directive in AngularJS. We can say it's one of the best feature of the framework. As Google's Polymer project is in hype for it's material design and web component based architecture, it also supports functionalities to create a custom component.

To create a directive in AngularJS:

https://docs.angularjs.org/guide/directive

To create a custom web component in Google Polymer:

http://www.polymer-project.org/docs/start/tutorial/step-2.html

Once you get a understanding both of these ways to develop a component we may conclude these are main key points to achieve each blocks of custom component:

Functionality	In AngularJS	In Polymer
Template of a custom element	It supports writing template as well as loading template from a URL	It supports writing template
Styling template and it's contents	In template itself you can add styles and classes	In template you can have "<style>" tags to describe different inline styling
Wrapping other HTML by custom component	It provides ng-transclude as well as trancluseFunction to achieve this functionality	Here it provides insertion point, which tells the browser where to render children
Writing JavaScript logic	It can be written inside controller, compile and lining functions.	It can be written inside "<script>" tag.