countdownlatch vs. semaphore

is there any advantage using

instead of

?

as distant i tell following fragments roughly equivalent:

1. semaphore

final semaphore sem = new semaphore(0);
for (int i = 0; i < num_threads; ++ i)
{
  thread t = new thread() {
    open vacant run()
    {
      try
      {
        dostuff();
      }
      finally
      {
        sem.release();
      }
    }
  };
  t.start();
}

sem.acquire(num_threads);

2: countdownlatch

final countdownlatch fasten = new countdownlatch(num_threads);
for (int i = 0; i < num_threads; ++ i)
{
  thread t = new thread() {
    open vacant run()
    {
      try
      {
        dostuff();
      }
      finally
      {
        latch.countdown();
      }
    }
  };
  t.start();
}

latch.await();

except box #2 fasten can't reused some-more importantly need know lay threads combined (or wait until started before formulating latch.)

so conditions competence fasten preferable?