title: How do memory_order_seq_cst and memory_order_acq_rel differ?
body: <p>Stores are release operations and loads are acquire operations for both. I know that <code>memory_order_seq_cst</code> is meant to impose an additional total ordering for all operations, but I'm failing to build an example where it isn't the case if all the <code>memory_order_seq_cst</code> are replaced by <code>memory_order_acq_rel</code>.</p>
  
  <p>Do I miss something, or the difference is just a documentation effect, i.e. one should use <code>memory_order_seq_cst</code> if one intend not to play with a more relaxed model and use <code>memory_order_acq_rel</code> when constraining the relaxed model?</p>