Dart: Future<void> vs void execution

main.dart

import 'dart:async';

void main() {
  fn1();
  scheduleMicrotask(() {
    print('microtask after fn1');
  });
  fn2();
  scheduleMicrotask(() {
    print('microtask after fn2');
  });
}

Future<void> fn1() async {
  print('fn1');
}

void fn2() {
  print('fn2');
}