I am looking at angular 4.0 and I have done a bit of Web components with Polymer. Angular components and custom elements in Polymer look the same from use case point of view. The angular components also provide some framework specific lifecycle callbacks.
What are the difference if any ?
There is no relation between Angular components and web components. Angular components are only reusable in other Angular components.
There is an ongoing effort (currently only experimental) to change that - Angular elements https://moduscreate.com/blog/angular-elements-ngcomponents-everywhere/
See also
