title: What is the difference between rails structure.sql and schema.rb
body: <p>I am aware that schema.rb file is a ruby file and it get created and modified when a rake migration is run, but what about the structure.sql.  </p>
  
  <p>I have seen in some projects schema.rb and in others structure.sql and in some both files, where do they configure which file to create.  </p>
  
  <p>What exactly is the difference between the two.  </p>
  
  <p>Is structure.sql generated is specific to a particular DB.</p>