Async stream vs broadcast

gistfile1.dart

import 'dart:async';

void main() {
  final controller = new StreamController<int>();
  
  controller.add(10);
  controller.stream.listen((a) => print('receive: $a'));
  
  final contrtoller2 = new StreamController<int>.broadcast();
  
  contrtoller2.add(20);
  contrtoller2.stream.listen((b) => print('receive $b'));
}