title: What is the difference for export default/const/class extends?
body: <p>There is a very good Tutorial for Gatsby on their website. Everything works fine but I've a problem to understand the difference in the starter templates.</p>
  
  <p>What is the difference between the different react component usage in the starte templates? Why do they use <code>export default...</code> for the hello world example, <code>const IndesPage = () 0&gt; (</code> for the default starter and <code>class BlogIndes extends React.Componenent</code> for the blog example.</p>
  
  <p><strong>gatsby-starter-hello-world</strong></p>
  
  <p><code>export default () =&gt; &lt;div&gt;Hello world!&lt;/div&gt;</code></p>
  
  <p><strong>gatsby-starter-default</strong></p>
  
  <pre><code>const IndexPage = () =&gt; (
    ...
  )
  
  export default IndexPage
  </code></pre>
  
  <p><strong>gatsby-starter-blog</strong></p>
  
  <pre><code>class BlogIndex extends React.Component {
    render() {
      ...
  
      return (
        ...
      )
    }
  }
  
  export default BlogIndex
  </code></pre>