What is the difference between returns async method and returns await async method?

Question

I have a below methods which list customers and do something on this customers with using async/await.

public async Task Execute()
{
  var customers  = await ListCustomersAsync();
  foreach(var customer in customers)
  {
    //do other things
  }
}

private async Task<IEnumerable<Customer>> ListCustomersAsync()
{
  return await _db.ListCustomersAsync();
}

Below methods have same purpose with above but only difference is async/await. I did not use async/await but I awaited ListCustomersAsync2() method in Execute2() method.

public async Task Execute2()
{
  var customers  = await ListCustomersAsync2();
  foreach(var customer in customers)
  {
    //do other things
  }
}

private Task<IEnumerable<Customer>> ListCustomersAsync2()
{
  return _db.ListCustomersAsync();
}

So what is the difference between this methods? What is the difference between using async/await keywords in ListCustomersAsync method then await this ListCustomersAsync method and not using async/await keywords but still await ListCustomersAsync2 method.

Are this methods works same? Which one has more performance? Which one is suitable for best practices? Which one should I prefer?