title: is StringComparison.Ordinal the same as InvariantCulture for testing equality?
body: <p>From their brief summary descriptions, it sounds like the string comparison rules <code>StringComparison.Ordinal</code> and <code>StringComparison.InvariantCulture</code> are meant to differ in how they do <em>sorting</em> of strings. Is that <em>all</em>? i.e., does that mean we can use either string comparison rule when doing an equality comparison?</p>
  
  <pre><code>string.Equals(a, b, StringComparison....)
  </code></pre>
  
  <p>And for extra credit: does it make a difference to the answer if we compare <code>OrdinalIgnoreCase</code> and <code>InvariantCultureIgnoreCase</code>? How?</p>
  
  <p>Please provide supporting argument and/or references.</p>