title: Practical difference between parser rules and lexer rules in ANTLR?
body: <p>I understand the theory behind separating parser rules and lexer rules in theory, but what are the practical differences between these two statements in ANTLR:</p>
  
  <pre><code>my_rule: ... ;
  
  MY_RULE: ... ;
  </code></pre>
  
  <p>Do they result in different AST trees?  Different performance?  Potential ambiguities? </p>