title: Rails ActiveRecord::Migration what is the difference between index: true and add_index?
body: <p>What is the difference between</p>
  
  <pre><code>t.boolean :is_live, index: true
  </code></pre>
  
  <p>and</p>
  
  <pre><code>add_index :table_name, :is_live
  </code></pre>
  
  <p>If there is no difference, how come only the <code>add_index</code> is reflected in schema.rb. When I use <code>index: true</code>, I can't actually see the index in <code>schema.rb</code>. Should I only use the <code>add_index</code> method. </p>
  
  <p>When use the <code>add_index</code> method, I can see this in my schema.rb</p>
  
  <pre><code>add_index "table_name", ["is_live"], name: "index_table_name_on_is_live", using: :blahblah
  </code></pre>