New In Angular 6:

1. ng-template added, template deprecated

2. httpClient (httpClientModule)

3. Nothing Wrong with httpModule. Still use it.
4. It adds new functionalities - interceptor, response typing, etc.
5. more

1. new RsJx
2. could use RxJs-compact package for ng5 project so that no changed needed.

3. pipe operator

   this.http.get().pipe(
   map( (data)=> {}),
   catchError( (error) => { return throwError('error msg') } ),
   retry(3)
   )
   

   

4. { providedIn : 'root' } --> pass this inside @Injectable to provide service at root Module.

5. Angular Element

6. yet to complete this tutorial.

Summary - step to migrate from an5 to ng6