title: Realm.open vs new Realm
body: <p>In the context of a React Native app, using Realm locally only (so no realm object server for now). What is the difference between opening a realm using 
  <code>Realm.open({schema: [Car, Person]})</code> and creating a new Realm instance with <code>new Realm({schema: [Car, Person]});</code> When should I use one or the other? </p>
  
  <p>Looks like <code>Realm.open</code> is just a callback to make sure the syncronisation is done, so only needed for synced Realms?</p>
  
  <p>So far this is what I found:</p>
  
  <h2>Realm.open:</h2>
  
  <p>According to the <a href="https://realm.io/docs/javascript/2.2.0/api/Realm.html#.open" rel="noreferrer">doc reference</a> <code>Realm.open</code> means <em>"Open a Realm asynchronously with a promise. If the Realm is synced, it will be fully synchronized before it is available."</em> It's the way shown in the <a href="https://realm.io/docs/javascript/latest/#realms" rel="noreferrer">js docs</a></p>
  
  <h2>new Realm:</h2>
  
  <p>According to the constructor in the <a href="https://realm.io/docs/javascript/2.2.0/api/Realm.html" rel="noreferrer">doc reference</a>, <code>new Realm</code> will <em>Create a new Realm instance [...]. If a Realm does not yet exist [...], then this constructor will create it. Otherwise, the instance will access the existing Realm</em></p>
  
  <p>In the React example they use new: <a href="https://github.com/realm/realm-js/blob/master/examples/ReactExample/components/realm.js" rel="noreferrer">https://github.com/realm/realm-js/blob/master/examples/ReactExample/components/realm.js</a></p>